Uncanny Shabbos Regulations


clip_image002Question #1: A CANDID QUESTION!

Chayim calls me on the phone:

“Prior to our marriage, I was taught that one may open cans on Shabbos, provided one does not reuse the can, whereas my wife was taught that this is strictly forbidden. Since I was taught by someone very knowledgeable and observant, there is something inconsistent here that I would like to understand.”

Question #2: DON’T PULL THE RING!

“I was eating at someone’s house for Shabbos where they served soda in cans and opened them. I thought that this desecrates Shabbos, and was uncertain whether I could trust their kashrus. Could I?”


Analyzing the laws of Shabbos properly is a very enriching experience. In this article, I will touch on some aspects of the following melachos germane to the issues involved:

(1) Boneh, Construction

(2) Soseir, Destruction

(3) Makeh Bepatish, literally, striking with a hammer

We also need to explain an important principle of the Shabbos laws called mekalkeil – literally, ruining. In general, a melachah activity is prohibited min haTorah only when the direct results are beneficial. An act whose direct result is destructive is not prohibited min haTorah but only miderabbanan. For example, digging a hole in the ground when one needs the earth but is not interested in the hole is considered a destructive activity and therefore prohibited only miderabbanan.  The need to acquire dirt notwithstanding, the dug hole that results is not a positive development, but a negative one. This renders the burrowing mekalkeil and relegates it to a rabbinically prohibited activity. However, digging a hole to plant or to create a posthole is a positive benefit and therefore prohibited min haTorah.

In a similar vein, smashing a barrel to obtain its contents is prohibited only miderabbanan, regardless of the need to obtain the food inside, since the smashed barrel is a negative result.


The Torah violation of Boneh includes performing any type of home repair or enhancement, even only a minor repair (Shabbos 102b). Thus, it is prohibited min haTorah to hammer a nail into a wall in order to hang a picture (Rashi, Eruvin 102a s.v. Halachah). Similarly, one may not smooth the dirt floor of a house, because this enhances the “structure” (Shabbos 73b).

Constructing Movable Items

Does the melachah of Boneh apply only to items connected to the ground, or does it also apply to the construction of implements and other movable items?

My desktop dictionary defines “construct” as “to build or form by putting together parts.” Clearly, in English “construct” includes manufacturing implements, just as it includes building on the ground. Do the laws of Shabbos similarly recognize that assembling implements violates this melachah?

The Gemara (Beitzah 10a) cites a debate regarding this question. In halachic conclusion, we find the following basic approaches:

(1) The melachah of Boneh includes only building on the ground and does not include movable items (Rashi, Shabbos 47a s.v. Chayov; Beitzah 11b s.v. De’ein).

(2) Major construction of small movable items is prohibited min haTorah, but minor improvement is not (Tosafos, Shabbos 74b and 102b). What is considered “major construction”? Assembling something in a way that involves strength and skill constitutes Boneh. Therefore, manufacturing implements is prohibited min haTorah, since it involves both strength and skill to do the job properly, whereas making a minor repair to an implement is not included under Boneh.

Large = Connected

According to many authorities, there is another factor to consider: the size of the movable item (Rashi, Eruvin 35a s.v. Umasnisin). In their opinion, one may not perform even a minor repair or enhancement to a utensil so large that one does not usually move it when it is full to capacity. Thus, even a small repair to a refrigerator or a bookcase is prohibited min haTorah according to this opinion, since an item this large is halachically equivalent to something attached to the ground.


Soseir, demolishing or razing, is also one of the 39 melachos, since the Jewish people disassembled the Mishkan whenever they moved it from place to place (Shabbos 31b).

Thus, removing something from a structure, such as removing a nail from a wall, or lifting a window or door off its hinges, is prohibited on Shabbos.

Destructive is Constructive?

Many acts of Soseir ruin something, and according to the rule of mekalkeil mentioned above, are prohibited only miderabbanan. Of course, this leads us to ask:

How can Soseir be prohibited min haTorah as one of the 39 melachos; is not demolishing always a destructive act? The answer is that Soseir is prohibited min haTorah when the destruction is constructive, despite the apparent contradiction in terms. The disassembly of the Mishkan was an act of demolition, yet it was constructive, since Hashem wanted the Mishkan (and the Jewish people) to move to a new location. Similarly, demolition of a building is prohibited min haTorah, if the ultimate results are beneficial, such as razing part of a building in order to renovate it, or razing a building in order to build anew on the site. In such cases, the demolition provides an immediate benefit, since it clears the site for the new construction.

In cases where there are no immediate benefits from the demolition, it is still prohibited miderabbanan. Thus, wrecking a house to save someone trapped inside does not involve a Torah prohibition of Soseir, since the act is itself destructive. (The activity is, of course, permitted in any case, because of the life-threatening situation involved.)

The authorities dispute whether someone who destroys something out of anger violates Shabbos min haTorah or only miderabbanan. According to most Rishonim, this incurs only a rabbinic desecration of Shabbos, since there is no positive benefit from the destruction (Pri Megadim 314:11 in Eishel Avraham). Of course, this act is prohibited for a variety of reasons, including bal tashchis (unnecessary destruction) and damaging one’s character development (Shabbos 105b). There is a minority opinion of the Rambam, who holds that wrecking something out of anger incurs a Shabbos violation min haTorah. He rules that performing an act that makes its perpetrator feel better incurs a Torah violation and is not considered mekalkeil, even though the act is extremely damaging both to the object of his wrath and to himself.

Does Soseir apply to Portable Implements?

Having established that Soseir is prohibited min haTorah only when it creates a direct positive result, we now want to understand whether destroying a vessel is included under the melachah of Soseir. Note that I discussed earlier whether the melachah of Boneh applies only to items connected to the ground, or whether it also applies to the construction of movable items. I noted that the Gemara debates this issue, and that the Rishonim provide the following conclusions:

1. Some contend that the melachah of Boneh includes only building on the ground.

2. Others contend that major construction of small movable items is prohibited min haTorah, but a minor improvement is not.

3. Many authorities contend that this previous dispute refers only to small, easy to move implements, but that a large implement is definitely included min haTorah within the melachah of Boneh, even to perform a minor repair or enhancement.

Since Soseir is the opposite of Boneh, if constructing an item constitutes Boneh, according to the opinions above, then destroying it is Soseir.

Makeh Bepatish

Before we analyze the Gemara texts that impact on our original questions, we still need to discuss one other prohibition: the melachah of Makeh Bepatish, which includes a general prohibition of completing items, such as smoothing a surface to finish an item. One aspect of this melachah is that it prohibits making a nice opening in a vessel, such as boring an outlet hole in a storage drum (Shabbos 146a; Rambam, Hilchos Shabbos 10:16). The Gemara teaches that it is prohibited min haTorah to make an opening that is to be used in both directions, whereas making an opening to be used only in one direction is prohibited miderabbanan. As an example of the first type of opening, the Gemara mentions an opening made in a chicken coop, which allows ventilation of its fumes and also allows light and/or air into the coop. Boring an outlet hole in a storage drum, the case I just mentioned above, is a classic example of something prohibited only miderabbanan, since the opening is intended only to remove the product, but not to return it to the vessel. However, creating a new opening that is meant both to remove and return product incurs a Torah prohibition.

The Can Opener

With the principles we have learned, we can now examine the Talmudic sources that directly affect our original questions: May one open a can or other package on Shabbos to obtain its contents?

The Mishnah (Shabbos 146a) permits smashing open a barrel of figs on Shabbos to reach the food inside, provided one does not try to make a proper opening. As I noted earlier, attempting to make a proper opening certainly desecrates Shabbos. The question is whether one can simply break the barrel to reach its figs without attempting to make a nice opening. This Mishnah states that this is permitted.

However, in another discussion (Eruvin 34b) the Gemara rules that one cannot break open a container to obtain the food inside. Since manufacturing a proper vessel, even a small one, is prohibited min haTorah, smashing it remains prohibited even when one is smashing the vessel to obtain food. Although I explained above that this act is mekalkeil and therefore not prohibited min haTorah, it is still prohibited miderabbanan.

If so, how can the Mishnah permit smashing a barrel to obtain its contents?

There are two major approaches to answer this question. Tosafos explains that the Mishnah that permits smashing to obtain food is not referring to a proper vessel, but to one that was previously smashed and then feebly repaired by use of resin as glue. Reconstructing this type of container, known in Aramaic as a mustaki, would not violate a Torah violation of Boneh since it is not considered a proper vessel. As a result, smashing this barrel does not really violate Soseir, and therefore, one may do so in order to obtain the figs. However, the Gemara in Eruvin is dealing with a regular vessel and therefore forbids smashing the vessel to obtain the food inside. This approach of Tosafos is followed by the Shulchan Aruch (Orach Chayim 314:1), who concludes that one may smash open a mustaki to obtain food on Shabbos, but not a proper vessel.

Other authorities distinguish between the two cases in a different way and therefore reach a different halachic conclusion. In their opinion, the Mishnah in Shabbos is describing a small vessel (as defined above) and the Gemara in Eruvin a large one. They conclude that in order to enhance the pleasures of Shabbos, Chazal permitted smashing a small vessel to obtain food, but they prohibited smashing a large vessel. According to this approach, one may smash open any “small” container on Shabbos in order to obtain its contents.

How do we Rule?

The Mishnah Berurah concludes that it is prohibited to smash open even a small vessel to obtain food on Shabbos, following the conclusion of the Shulchan Aruch (Bi’ur Halachah 314:1). Other authorities rule that one should not admonish those who smash vessels to obtain their contents, since this common practice is based on a bona fide opinion (Aruch Hashulchan 314:8). All agree that one may not open the container in a way that creates a nice opening.

However, this approach does not satisfactorily explain those who permit opening cans on Shabbos, since neither of these opinions permits being mekalkeil to obtain food on Shabbos. They only dispute whether one should correct those who do smash small vessels. Is there any basis for those who allow the opening of cans on Shabbos?

Enter Chosalos

There is another basis to permit opening packaging on Shabbos. The Gemara mentions a halachah of chosalos, which are a type of basket made of palm branches (also known as lulavim) in which one places unripe dates to ripen or where one stores dried figs. The Gemara rules that one may rip these chosalos open on Shabbos. The question is why this is not considered destroying a vessel, which we concluded before is prohibited, at least lechatchilah.

The Kolbo explains that chosalos are considered an artificial peel or shell around the dates or figs. The rationale is that the chosal is tafeil, secondary, to the food it contains and therefore it is not considered to be a vessel. Just as one may remove the natural peel or shell of a fruit on Shabbos and it is certainly not making or destroying a vessel, so one may remove an artificial “peel” or “shell” on Shabbos. Thus, anything included under the heading of chosalos may be opened on Shabbos. The Magen Avraham states that the permission to open chosalos does not permit the breaking of a regular vessel.

Can our contemporary packaging be compared to the law of chosalos? To answer this we need to have a clear definition of what defines a regular vessel and what defines chosalos.

Opening Cans

In a lengthy teshuvah on the subject, Rav Moshe Feinstein defines a chosal as any item that is not reused for any other product; everyone disposes of the chosal once its product is used up. A “regular” vessel is one that people reuse for another product. According to this definition of a chosal, even a tin can is a chosal, if everyone disposes of the can after finishing the original contents, and certainly if everyone disposes of the can immediately after opening it. Following this analysis, opening cans on Shabbos does not violate the melachos of Shabbos, since tin cans are not reused for other products. (In Rav Moshe’s teshuvah on the subject, he implies that this halachah is true, even if one returns the original product to the chosal.) Rav Moshe himself concludes at the end of his teshuvah that one should open these packages before Shabbos, explaining that people might misunderstand the laws and mistakenly open packaging that is prohibited. However, in the case of someone who made a sheva berachos or who invited guests and finds, to his embarrassment, that he does not have enough food to serve, he permits having a gentile open the cans and other containers on Shabbos (Shu’t Igros Moshe 1:122; for a similar approach, see Shu’t Chelkas Yaakov 3:8).

On the other hand, other authorities contend that any strong vessel is not considered a chosal.

We must note that in another responsum, Rav Moshe rules that one may not open a milk or juice carton on Shabbos, since this creates a spout (Shu’t Igros Moshe, Orach Chayim 4:78). Why is this not similar to opening a chosal, which Rav Moshe permits? It seems that although he permits opening a chosal on Shabbos, he does not permit opening it in a way that forms a nice opening. (By the way, we should note that, according to what I have just explained, Rav Moshe would prohibit opening cans with pull up rings  since pulling the lid off forms a nice opening.)

Soda Cans

Rav Shelomoh Zalman Auerbach permits opening soda cans on Shabbos (Shulchan Shelomoh 314:7:4). He makes no mention of the concerns voiced in Rav Moshe’s closing paragraphs (that people might err and exceed the perimeters of his leniency) and therefore concludes that even Jews may open them on Shabbos.

On the other hand, the Chazon Ish (Orach Chayim 51:13) contends that opening any cans violates the Torah prohibition of making an opening. He explains two different reasons why opening cans is prohibited min haTorah:

1. The opening is meant to be used both ways: it allows air inside the can to break the vacuum and it allows the product out.

2. Opening a can is like creating a new vessel, since the closed can is useless, and opening it creates a serviceable vessel. Although he acknowledges that few people reuse cans, they can be reused, particularly by resourceful people (Orach Chayim 51:11).

Rav Shelomoh Zalman disputes the rationale that a soda can opening is considered “two-way”, since the entire purpose of allowing the air in is to enable the product to exit. Also, he does not consider the resultant opening a “nice opening”, since it is simply a means of removing the product from the container.

In conclusion, the intent of this article is not to provide a definitive pesak regarding these issues – every person should ask his posek. Our goal is to give people a better understanding of the issues involved and an appreciation of their rav’s ruling, whatever it may be.

Assembling Portable Cribs and Adjusting Shtenders on Shabbos

Question #1: I am having a lot of company for Shabbos and we have a small house. During Shabbos, I would like to remove the extra leaves from the table and set up the “porta crib,” and then in the morning fold up the crib and put the table leaves back. May I do this on Shabbos?

Question #2: I have an adjustable shtender that I usually leave at the same height. May I adjust it on Shabbos?

Question #3: The house is very crowded and stuffy because we are celebrating a kiddush. May I remove a door or a window to allow some additional ventilation? (I was asked this shaylah in Israel where doors and windows are hinged in a way that they are easily removable.)

Question #4: May I remove the pieces of glass from a broken window on Shabbos?

Before discussing these shaylos, we need to explain the halachos of construction on Shabbos, and how they apply to movable items such as household furnishings and accessories.


Boneh, building or constructing, is one of the 39 melachos of Shabbos that are derived from the construction of the Mishkan. Included in this melacha is performing any type of home repair or enhancement, even if only a minor repair (see Gemara Shabbos 102b). Thus, it is prohibited min haTorah to hammer a nail into a wall in order to hang a picture (Rashi, Eruvin 102a s.v. halacha). Similarly, one may not smooth the dirt floor of a house because this enhances the “structure” (Gemara Shabbos 73b).

Sosair, demolishing or razing, is also one of the 39 melachos, since Bnei Yisroel disassembled the mishkan whenever they moved it from place to place (Gemara Shabbos 31b). Therefore, any demolition of a building is prohibited min haTorah if the ultimate results are beneficial, such as razing part of a building in order to renovate it.

If there are no benefits to the demolition, it is still prohibited midirabbanan. Thus, wrecking the house because someone is angry violates Shabbos only midirabbanan (according to most Rishonim) since there is no positive benefit from the destruction (Pri Megadim 314:11 in Eishel Avraham). It is also prohibited because of other reasons, such as bal tashchis (unnecessary destruction) and being bad for one’s middos (see Gemara Shabbos 105b).

We already have enough information to answer questions #3 and #4 above, regarding removing a window to ventilate the house and removing pieces of glass from a broken window. Both of these activities are prohibited min haTorah since they involve the melacha of sosair for positive results. Therefore, a Jew may not remove the window or the broken glass unless there is a life-threatening emergency. If the broken window is dangerous (but not life threatening), one may ask a non-Jew to remove the broken pieces of glass.


Do the melachos of boneh and sosair apply to movable items, keilim (sing., kli), as well, or only to buildings? In other words, does the Torah’s prohibition refer only to something connected to the ground, or does it include the construction of a movable item?

This question is disputed in the Gemara and by the Rishonim, who debate whether keilim are included in the prohibition of building and destroying on Shabbos (Gemara Beitzah 10a). There are three basic opinions:

1. Keilim are not included in the prohibition of boneh and sosair.

2. Keilim are totally included in the prohibition of boneh and sosair.

3. A compromise position in which total construction or destruction of a kli is prohibited min haTorah, but minor improvement is not (Tosafos Shabbos 74b and 102b). The halacha follows this opinion (Shulchan Aruch 314:1).


Assembling or improving a kli in a way that involves strength and skill constitutes boneh, and disassembling it involves sosair. Therefore, it is prohibited min haTorah to assemble a piece of furniture in a way that its parts are now extremely tight since this involves strength and skill to do the job properly. Similarly, replacing the handle on a hoe or other appliance is prohibited min haTorah since it requires skill and strength to do the job properly (Gemara Shabbos 102b).

What is considered tight? It appears from sources that anything as tight as one would nail it together is considered tight enough to be prohibited min Hatorah.

Assembling furniture without tightening the pieces is not prohibited min haTorah, but is prohibited midirabbanan out of concern that one might tighten them (Tosafos Shabbos 48a s.v. ha; Hagahos Ashri Shabbos 3:23). Therefore, one may not assemble a bed, crib, or table even without tightening the pieces since these pieces of furniture are usually tightened (Kaf HaChayim 313:63). However, there is a minority opinion that permits assembling such an item very loosely (Chazon Ish).


One may not assemble a crib on Shabbos. Assembling it in a very tight way may involve a Torah prohibition, whereas assembling it without tightening the pieces is prohibited midirabbanan since one might assemble it tightly. (However, porta cribs which are meant to be assembled and taken apart, have a different halacha as I will explain shortly.) According to most authorities, if one usually tightens the crib very tightly, it is prohibited to assemble it even very loosely, whereas according to the Chazon Ish, one may assemble it loosely.


Repairing a broken appliance on Shabbos follows the same guidelines as assembling. Therefore it is prohibited when the repair requires skill and strength even if one repairs it in a temporary way.

Therefore, if the leg of a bed or table fell out, one may not reinsert it even temporarily out of concern that one might repair it permanently (Shulchan Aruch 313:8). In this instance, Chazal decreed that the bed or table itself becomes muktzah in order to ensure that someone does not repair it (Rama 308:16). Again, according to the Chazon Ish, one may insert it loosely.


There are two exceptions to this rabbinic prohibition, when one may assemble or repair an item in a non-permanent way. The first is on Yom Tov (Tosafos Beitzah 22a; Shulchan Aruch 519:2, Magen Avraham and Gr”a ad loc.). One may use a temporary repair to fix a furniture item for a Yom Tov need.


A leg fell off the table on Yom Tov. Repairing the table in a proper way is prohibited min haTorah, and therefore on Shabbos I may not even reinsert the leg into the table in a temporary way. However on Yom Tov, I may reinsert the leg without performing a proper repair if this is the most convenient table to use.


If the broken or disassembled item is usually repaired or assembled without strength or skill, I may repair it in a temporary fashion. Chazal did not forbid this since it is unlikely that it will cause any Torah violation (Gemara Shabbos 47b with Tosafos).


In the time of the Gemara there existed a type of bed called “a coppersmiths’ bed.” Apparently, it was common that coppersmiths traveled from place to place making their living as iterant repairmen, and took portable beds with them that they reassembled at each destination. May one assemble this bed on Shabbos or is it considered construction? The Gemara quotes a dispute on the subject. According to the Tanna who contends that keilim are totally included in the prohibition of boneh and sosair, one may not assemble these beds on Shabbos (Shabbos 47a).

However, the conclusion is that one may assemble these beds on Shabbos. That is because these beds were never assembled very tightly and therefore it is not considered boneh to construct them, nor does it qualify as a rabbinic prohibition. However, an appliance that was assembled very tightly would be prohibited to assemble even loosely since it might be tightened (Tosafos ad loc.; cf., however, Chazon Ish).

Assembling the typical porta crib is similar to assembling a coppersmiths’ bed. Thus, one may assemble a porta crib on Shabbos and fold it up afterwards.


Inserting table leaves also does not require skill or strength and is therefore permitted on Shabbos. However, some tables have a clamp to tighten the table after inserting or removing the leaf. This might be considered tightening enough to be prohibited and I refer you to your local Posek.


About three hundred and fifty years ago, the poskim began discussing appliances held together with screws. Around this time a drinking cup became available where the cup part screwed into a base. Does screwing this appliance together on Shabbos constitute boneh?

The halacha question here is as follows: Although this cup does not require someone particularly strong or skilled to assemble and disassemble, screwing the base on makes the cup into a well-made permanent appliance. Thus, the screw enables someone who is not particularly skilled to build a strong appliance.

The early poskim debate this issue. The Magen Avraham (313:12) rules that screwing an appliance together constitutes a melacha min haTorah (see Shaar HaTziyun 313:32), Maamar Mordechai disagrees. In practice however, Maamar Mordechai concludes that one should follow the stringent ruling of the Magen Avraham, and this is the accepted halachic practice. Thus, screwing the cup together is considered manufacturing a cup.

Similarly, today one can purchase furniture that one takes home and assembles by oneself. One might argue that assembling this furniture is prohibited min haTorah even though it is made in a way that an unskilled person can assemble it. Thus, the definition of “skill and strength” is not whether the assembler needs to be skilled or strong, but whether the appliance is made into a permanent, well-made appliance.


Focusing a pair of binoculars involves turning a screw to make it tighter and looser. Does this violate boneh on Shabbos?

The poskim rule one may focus binoculars on Shabbos (Kaf HaChayim 313:73; Ketzos HaShulchan 119:12). They explain that there is a qualitative difference between screwing the base onto the cup, which creates an appliance, and screwing the binoculars, which is the method of using it. One may use an appliance, just as one may use a house by opening and closing the doors and windows. This is not building an extension onto the house, but is rather considered normal, daily usage.


Many shtenders are tightened and loosened by the use of a screw. May one adjust the shtender by loosening and tightening the screw? Does it make a difference how often one adjusts the height?

According to Rav Shlomo Zalman Auerbach and Rav Vozner, one may adjust the height of the shtender on Shabbos since this is considered using the shtender, not making a new appliance (Shulchan Shlomoh 313:7; Shu”t Shevet HaLevi 6:32; cf. Minchas Yitzchok 9:38, who prohibits).



I forgot to fill the saltshaker before Shabbos, and now I realize that it is empty. May I unscrew the saltshaker on Shabbos to fill it, or is this considered demolishing and repairing the saltshaker?

Rav Shlomo Zalman Auerbach ruled that it is permitted to open, refill and close the saltshaker on Shabbos without violating boneh. Although the saltshaker is indeed screwed closed, it is typically not screwed as tightly as one screws furniture or the cup we described earlier (Minchas Shlomoh 1:11:4 s.v. gam nireh). The same applies to opening and closing a baby bottle. Although it is opened and closed by screwing, since it is intended to be opened and closed constantly, it is not considered demolishing and reconstructing it.


We may ask ourselves, why is the screwing of a cup together or removing a window off its hinge considered a melacha? Both cases only take seconds to complete and are not at all strenuous.

Rav Samson Raphael Hirsch (Shmos 20:10) notes that people mistakenly think that work is prohibited on Shabbos so that it should be a day of rest. He points out that the Torah does not prohibit doing avodah, which connotes hard work, but melacha, which implies purpose and accomplishment. Shabbos is a day that we refrain from constructing and altering the world for our own purposes. The goal of Shabbos is to allow Hashem’s rule to be the focus of creation by refraining from our own creative acts (Shmos 20:11). Through not building for one day a week, we demonstrate and acknowledge the true Builder of the world and all it contains.