Mechitzah Arai

Shabbat (17:7) | Yisrael Bankier | a year ago

The Mishnah (17:7) records a debate about using a board to seal a window on Shabbat. According to R' Eliezer, the border must be tied to the wall and be hanging above the floor in order to use it to seal the window. The Bartenura explains that were that not the case, R' Eliezer maintains that it would appear as though one was mosif al ha'binyan -- adding to the construction -- and even a temporary addition is prohibited. The Chachamim however disagree. The Bartenura explains that as long as the board was set aside for that purpose, it can be used to close up the window. The Chachamim do not forbid temporary adages.

The Gemara (125b) explains that everyone agrees the one is not allowed to construct a temporary ohel on Shabbat. The debate in our Mishnah is whether one can add to an existing one. Rashi (s.v. she'ein) comments that the issue of constructing a temporary ohel refers specifically to the addition of a roof. For example, placing a mat on top of four poles to create a shaded area. Erecting a makeshift wall for privacy however would be permitted.

The Tosfot (s.v. hakol) however ask that we find in Eiruin (44a) that the Gemara prohibits adding a third wall to a sukkah (yet permits add a fourth). We find therefore that it is indeed prohibited to construct a temporary wall.

Rabbeinu Tam explain that it is prohibited to construct even a temporary wall. The difference between the third and fourth wall is that the third wall affected a legal change -- it is now a kosher sukkah. Consequently, it is considered as if it is like the construction of an ohel. Regarding the addition of the fourth wall, since the sukkah is already valid, it is considered like an addition to an existing ohel.

Interestingly, one could defend Rashi based on his comment in Eiruvin. There Rashi explains that when the sukkah had only two walls it was not defined as an ohel. It is the construction of the third wall that defines it as an ohel. In other words, Rashi can still maintain that the issue is constructing a temporary ohel and not constructing a temporary wall. In this case however, when one adds the third wall, it defines the entire construction as an ohel.

The Maginei Shlomo explains that Rashi as follows. Even if there is a sechach above a sukkah that only has two walls, since it is not valid, it is not considered an ohel. The addition of the third wall defined that sechach above as sechach and the defines the construction as an ohel. In other words, when Rashi permits the erection of a temporary wall, it is only when it is not connected to the construction of an ohel, e.g. for privacy. If however the addition of the wall impacts the definition of the entire construction as an ohel then he would agree it is prohibited.

Even though the case of the sukkah was a halachic one, the Maginei Shlomo expands his understanding of Rashi further. The Maginei Shlomo understand that if a temporary ohel was constructed, but incomplete until the wall was added, then Rashi would agree that it would be prohibited. For example, if one placed a mat over four poles for shade, but it was insufficient until an additional wall is added, Rashi would agree that it would be prohibited to add that wall, much like the third all in the sukkah, since doing so would complete the ohel.

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