THE WIDTH OF A SUKAH [Sukah:width]
7b - Abaye: The following require (or allow) a Sukah to be Diras Keva - Rebbi, R. Yoshiyah, R. Yehudah, R. Shimon, R. Gamliel, Beis Shamai, R. Eliezer and Others:
Rebbi requires a Sukah to be at least four by four Amos;
Beis Shamai disqualify a Sukah if Rosho v'Rubo of a man are inside and his table is in the house; Beis Hillel are Machshir.
3a - Rav Shmuel bar Yitzchak: A Sukah must be able to hold Rosho v'Rubo and his table.
Question (R. Aba): Do you teach like Beis Shamai?!
Rav Shmuel: Yes! Do not veer from it (the Halachah follows Beis Shamai)!
Question (Rav Nachman bar Yitzchak): You assume that Beis Shamai and Beis Hillel argue about small Sukah which cannot fit Rosho v'Rubo and his table. Perhaps all require the Sukah to be big enough to fit them! Beis Shamai decree to disqualify when he sits in the Sukah and the table is outside, lest he be drawn after the table, and Beis Hillel do not decree.
Support (Mishnah): If Rosho v'Rubo of a man are inside and his table is in the house, Beis Shamai are Posel and Beis Hillel are Machshir.
According to Rav Shmuel, it should say 'if a Sukah cannot hold Rosho v'Rubo and his table...!'
Counter-question: They argue about a small Sukah! (Chachamim of) one Beraisa require a Sukah to hold Rosho v'Rubo and his table, and Chachamim of another Beraisa require only that it hold Rosho v'Rubo. Surely, the first Beraisa is Beis Shamai and the latter is Beis Hillel!
Support (Mar Zutra - Mishnah): ...Beis Shamai are Posel and Beis Hillel are Machshir.
If they argue about a decree, the Tana'im should argue about whether or not he was Yotzei!
Question: We proved above that they argue about a decree!
Answer: They argue about both of these. The Mishnah is abbreviated. It means, if Rosho v'Rubo are inside and his table is in the house, Beis Shamai say that he was not Yotzei and Beis Hillel say that he was Yotzei. If a Sukah cannot hold Rosho v'Rubo and his table, Beis Shamai are Posel and Beis Hillel are Machshir.
16b: R. Ami: A plank just over four Tefachim wide may be used for a wall of a Sukah. (E.g. to use it for the north wall) one places it within three Tefachim of the (east) wall, and it is like Lavud.
Question: What is the Chidush?
Answer: He teaches that the Shi'ur (for the width of a Sukah) is seven Tefachim.
Rif (3b) and Rosh (1:10): The Halachah follows Beis Shamai who disqualify if Rosho v'Rubo were in the Sukah and his table was outside. They do not require Diras Keva; rather, it is a decree lest one be drawn after the table.
Rif (13a): We concluded that they argue about a small Sukah and about whether or not we decree to disqualify when his table is in the house. The Halachah follows Beis Shamai regarding both of them, for the reason is the same. The Shi'ur of Rosho v'Rubo and his table is seven Tefachim by seven Tefachim.
Rebuttal #1 (Ran): If the reasons for the arguments were the same, the Gemara would not need to teach two arguments! Beis Shamai disqualify a small Sukah because they require Diras Keva. The Gemara rules like Beis Shamai, for this level of Diras Keva is required. It did not say whom the Halachah follows regarding the decree. The general rule applies that the Halachah follows Beis Hillel.
Rebuttal #2 (Rosh 1:1): On 3a, one Beraisa requires a Shi'ur for Rosho v'Rubo and his table, and the other Beraisa requires only for Rosho v'Rubo. In both of them Rebbi requires four Amos; this is big enough for also the table to be in the Sukah. Surely, Beis Hillel and Beis Shamai also discuss when the table is inside, and nevertheless Beis Shamai disqualify even though there is no concern lest he be drawn out of the Sukah. This shows that the reasons for the arguments are separate.
Defense #1 (Hasagos ha'Ra'avad): Abaye holds that the Halachah does not follow any of the opinions that require Diras Keva. The Halachah does not follow Abaye, therefore we can explain Beis Shamai simply, unlike Abaye. Beis Shamai disqualify a large Sukah lest one be drawn after the table. All the more so they disqualify a small Sukah for the same reason! One could say that the Halachah follows Beis Shamai only regarding a small Sukah, in which there is more concern lest he be drawn out. However, It is more reasonable to say that the Halachah follows Beis Shamai in both cases since there is a common reason.
Defense #2 (Milchamos Hash-m 3b): There is a common reason for both. If the Sukah is too small, it is not fit for eating normally (at a table) unless the table will be outside, which Beis Shamai disqualify. Since it is not Kosher for eating normally, it is totally Pasul. The argument was taught regarding big and small Sukos to teach the extremity of the opinions, that Beis Shamai Posel even a big Sukah and Beis Hillel allow even a small Sukah. Since the Gemara did not distinguish (whom the Halachah follows) between a big and small Sukah, we may not distinguish.
Defense #3 (Ritva 3a DH Ika): Perhaps Abaye and Rava say the same thing in different words. Abaye says that Beis Shamai require a Sukah which could be Keva, i.e. in which there is no concern lest one be drawn after his table, for there is room for him and his table.
Sha'ar ha'Tziyon (OC 634:8): Milchamos Hash-m connotes that a Sukah big enough only for Rosho v'Rubo is Pasul mid'Oraisa. This is why the Gemara never says that the Shi'ur of seven Tefachim is mid'Rabanan. Perhaps the Rif could agree with this; nevertheless, there is a common reason for the mid'Rabanan decree and the Shi'ur mid'Oraisa. However, the Ran and Ritva connote that the Rif holds that the Shi'ur is only mid'Rabanan.
Rambam (Hilchos Sukah 4:1): A Sukah must be at least seven by seven Tefachim wide. It can be as wide as desired.
Source (Magid Mishnah): The Halachah is, it must hold Rosho v'Rubo and his table. The Gemara (16b) says that seven Tefachim is the Shi'ur.
Rambam (Hilchos Sukah 6:8): One may not eat if Rosho v'Rubo are in the Sukah and his table is in the house or outside the Sukah; if he ate, it is as if he ate outside the Sukah, unless his table is in the Sukah. This is a decree lest he be drawn after his table, even if his Sukah is very big.
Rosh (1:1): A Sukah must hold Rosho v'Rubo and his table. The Yerushalmi allots six Tefachim for a person and one Tefach for the table. Rav Amram Gaon says that this is one of six places where the Halachah follows Beis Shamai. However, regarding a big Sukah the Halachah follows Beis Hillel who do not decree to disqualify when the table is in the house.
Shulchan Aruch (OC 634:1): A Sukah less than seven by seven Tefachim is Pasul. There is no upper limit to the length and width.
Source #1 (Beis Yosef DH u'Mah she'Chasav ul'Inyan): If there was an upper limit to the length and width the Gemara would have specified.
Source #2 (Gra DH ul'Inyan): The Gemara (27b) expounds that all of Yisrael can sit in one Sukah, i.e. a Sukah can be enormous.
Magen Avraham (1): If a big Sukah has a part that is less than seven by seven Tefachim one may not sit there, for it is narrow and uncomfortable.
Bi'ur Halachah (DH Sukah): Derech ha'Chayim says that one may sit in a corner that is seven wide even if it is not seven long, just like a round Sukah is Kosher even though it is not seven long near the wall. This is wrong; a round Sukah is not cramped, but a narrow Sukah is cramped. However, one can be lenient if he is in a wide Sukah and his table is in a small corner of it, for some Poskim do not decree even when his table is in the house.
Shulchan Aruch (OC 634:4): If a man ate when Rosho v'Rubo were inside the Sukah and his table was outside, it is as if he ate outside the Sukah. This is a decree lest he be drawn after his table, even if his Sukah is very big.
Magen Avraham (2): If his table is partially in the Sukah there is no decree.
Source: We are not concerned lest he be drawn out of the Sukah, since one Tefach suffices for a table. Also, many allow the table to be in the house if the Sukah is big.
Kaf ha'Chayim (11): The Birkei Yosef and the Ra'avad require the majority to be in the Sukah.
Bi'ur Halachah (DH k'Ilu): If one transgressed the decree, Tosfos (3a DH d'Amar) holds that he was not Yotzei mid'Oraisa. The Ran and Ritva say that he was not Yotzei mid'Rabanan.