GEMARA

10b - Version #1 - Shmuel: One may sleep in a Sukah under a Kilah (a canopy) even if it has a (horizontal) roof. This is only if it is less than 10 Tefachim tall.

Question (Mishnah (20b)): One who sleeps under a bed in a Sukah is not Yotzei.

Answer: Shmuel said that the Mishnah discusses a bed 10 Tefachim tall.

Question (Mishnah): If one spread a sheet over Kinof, it is Pasul (one may not sleep underneath it. Kinof is a framework of poles, One vertical pole is placed at each of the four corners of a bed, and horizontal poles connect the tops of the vertical poles.)

Answer #1: This is if the Kinof is 10 Tefachim tall.

Objection (Beraisa): Naklitin has two (vertical) poles (one at each end of the bed, and a third horizontal pole on top of them), and Kinof has four. If one spread a sheet over Kinofos it is Pasul; if one spread over Naklitin it is Kosher, as long as the top is less than 10 Tefachim.

Inference: Kinof is forbidden even when (Naklitin are Kosher, i.e.) it is less than 10 Tefachim!

Answer #2: Kinofos even less than 10 Tefachim forbid because they are fixed.

Question: A Sukah over a Sukah is fixed, yet Shmuel said that the Pesul is (only if the top Sukah is 10 Tefachim tall), like (the Shi'ur of) Hechsher Sukah!

Answer: 10 Tefachim are needed to Mevatel an (entire) Sukah. Here, to be considered an Ohel (to forbid sleeping under it) even less than 10 suffices.

11a - Version #2 - Shmuel: One may sleep in a Sukah under a Kilah because it has no roof. This is even if it is 10 tall.

Question (Beraisa): Naklitin has two poles, and Kinof has four. If one spread a sheet over Kinofos it is Pasul. If one spread over Naklitin it is Kosher, as long as the top is less than 10 Tefachim.

Inference: Naklitin are forbidden if they are 10 Tefachim, even though they have no roof!

Answer: Naklitin are different (than Kilah) because they are fixed.

Question: If Naklitin are fixed, they should be like Kinofos!

Answer: Naklitin are more fixed than Kilah, but they are less fixed than Kinofos.

Rabah bar Rav Huna: One may sleep in a Sukah under a Kilah even if it has a roof and even if it is 10 tall.

Question: This is like R. Yehudah, who permits to sleep under a bed. Rabah should have explicitly said that the Halachah follows R. Yehudah!

Answer: Had he said that the Halachah follows R. Yehudah, one might have thought that R. Yehudah permits only under a bed, because it is not made for using the space under it, but he would forbid under a Kilah. Therefore, Rabah teaches that the reason for R. Yehudah is that an Ohel Arai does not Mevatel a fixed Ohel, be it a bed or Kilah.

RISHONIM

Rif (5b) and Rosh (1:19): Kinofos has four poles. A sheet spread over Kinofos is Pasul because it is a Sukah in a Sukah. Naklitin has two poles. A sheet spread over Naklitin is not like an Ohel, for it has no roof, therefore it is Kosher. The Yerushalmi says that just like one may spread a sheet over his elbows and this is not a problem, one may spread a sheet over Naklitin.

Ba'al ha'Ma'or: Naklitin that are 10 Tefachim disqualify. Kinofos disqualify even if they are less than 10 Tefachim because they are fixed.

Milchamos Hash-m: The Rif permits a sheet over Naklitin, even if they are 10 tall. This is unlike the Beraisa. He learns from Shabbos. One may not make an Ohel (with a flat roof) on Shabbos even if it is less than 10 Tefachim. It is also an Ohel regarding Tum'ah. Even regarding Sukah it is Pasul only because it is not fit for Dirah. Therefore, if such a Ohel is Keva and one is under it in the Sukah, he is not considered to be under the Ohel of the Sukah. One may make a slanted roof on Shabbos. The opinion that a sloped roof is not an Ohel holds that it is not even an Ohel Arai.

Rif (6a): One may sleep under a Kilah in a Sukah even if it has a roof, as long as it is less than 10 tall. Similarly, even if it is 10 tall if it does not have a roof it is permitted, like a Tzerif (a tent with sloped walls).

Rosh (1:20): It seems that the two versions do not argue. Both forbid only if it has a roof and is 10 tall. This is like the Rif. The Ritz Gei'us says that all our Rebbi'im rule like the second version. It is Pasul only if it has a roof, whether or not it is 10 tall. This cannot be! Shmuel answered that one who sleeps under a bed is not Yotzei if it is 10 tall.

Note: The question and answer about one who sleeps under a bed is only in the first version. Nevertheless, the Rosh brings a proof from it. Since a bed has a roof, this is the only way Shmuel can answer the Mishnah!

Rif (10a) and Rosh (2:1): One who sleeps under a bed 10 Tefachim tall in a Sukah is not Yotzei because it is like a Sukah in a Sukah.

Rebuttal (Ba'al ha'Ma'or): No, he is not Yotzei because the bed is an Ohel. The person is in the bed's shade, not in the shade of the Sukah.

Defense (of Rif - Milchamos Hash-m): If the problem was because he is under a different Ohel, this would apply even if the bed is less than 10! For other laws, an Ohel need not be 10 Tefachim. Rather, this Ohel is Mevatel the Sukah because it is like a Sukah in a Sukah. When a Sukah is over a Sukah, the top Sechach was not made to be shade over the bottom Sukah, therefore it disqualifies it.

Rebuttal (Ran DH Gemara): If so, we should say that just like a Sukah over a Sukah disqualifies only if there are 10 Tefachim in between, the same applies to an Ohel in a Sukah. However, we say so only regarding a bed because it is not meant to be an Ohel and a Kilah because it is not Kavu'a. Kinofos disqualify even if there are less than 10!

Rambam (Hilchos Sukah 5:23): If a bed in a Sukah is 10 Tefachim tall, one who sleeps under it was not Yotzei, because it is like a Sukah inside a Sukah. Similarly, one may not sleep under a Kilah 10 tall even if its roof is only a Tefach. Similarly, if one spread a sheet over four poles, if it is 10 tall this is like a Sukah inside a Sukah.

Rambam (24): However, if one spread a sheet over two poles, or if a Kilah does not have a roof a Tefach wide, one may sleep under it regardless of its height.

Ran (DH Mutar): A Kilah is not fixed, therefore it is forbidden to sleep under it only if it has a roof and it is 10 tall. Nakiltin are more fixed. It is forbidden to sleep under them if they are 10 tall, even though they have no roof. Kinofos are fixed and have a roof. It is forbidden to sleep under them even if they are less than 10.

Question (Ran, ibid.): The Rif and Rambam permit them in any case. This is difficult!

Answer (Magid Mishnah): The Rambam and Rif do not distinguish Kilah, Naklitin and Kinofos. They hold that the Beraisa and the Sugya are like the opinion that considers a sloped roof to be an Ohel and therefore permits a Sukah like a Tzerif, but this is not the Halachah. We are concerned only when there is a Ohel a Tefach wide, and only if it is 10 tall. It does not matter whether or not it is fixed.

Question (Lechem Mishneh): Kinofos have a roof. Why does the Rambam permit when they are less than 10? The Gemara forbids, because they are fixed!

Answer (Lechem Mishneh): Just like Kevi'us does not help to permit a Sukah when it has no roof, it does not help to forbid due to a Sukah in a Sukah.

Question (Taz OC 627:3): Why did the Gemara need to say that Kinofos are more fixed than Naklitin? It could say that both are equally fixed, and disqualify if they have one attribute, a roof or 10 Tefachim. Kinofos always forbid since they have a roof, but Naklitin require 10 Tefachim because they have no roof!

POSKIM

Rema (OC 627:1): One must sit in the air of a Sukah.

Mishbetzos Zahav (1,2): The Bach says that the Tur and Shulchan Aruch say that being under a bed is like Sukah under a Sukah, like the Rif, Rambam and Rosh. This appears correct. The Taz explains the Tur and Shulchan Aruch like the Ba'al ha'Ma'or, who disqualifies because he is not in the shade of the Sukah. The Bach says that Sukah under a Sukah is Pasul mid'Oraisa, but not being in the shade of the Sukah is only mid'Rabanan. It is possible that even Sukah under a Sukah is Kosher mid'Oraisa. If this is the only way one can fulfill the Mitzvah, Chachamim's decree does not apply to him. Perhaps he may even bless.

Shulchan Aruch (1): One who slept under a bed in a Sukah was not Yotzei if the bed is 10 Tefachim tall.

Taz (3): The Ran says that a bed is fixed. Since it is made for (lying) on top of it, it disqualifies only if it is 10 tall. This is difficult. The Gemara did not answer that it is more stringent than Kilah because it is fixed! Rather, it is not considered fixed because people move it from place to place. This is unlike Kinofos and Naklitin, which are never removed from their place on the bed.

Kaf ha'Chayim (4): If the bottom of the bed is 10 above the ground it is an Ohel, even if the side walls of the bed are less than a Tefach thick. The same applies to a table.

Shulchan Aruch (2): One who slept under a Kilah was Yotzei if it is not 10 tall or if it does not have a roof a Tefach wide.

Mishnah Berurah (5): The 10 Tefachim are measured from the ground.

Kaf ha'Chayim (9): The Agudah says that if it is a Tefach wide within three of the top, or if the sheet is at least a Tefach above the floor this is considered having a roof (and Lavud creates walls). Levushei Serad explains that the Magen Avraham calls this a mistake. Perhaps the Agudah is merely stringent.

Magen Avraham (2): One may not nail boards in place to be Sechach even if they are less than four Tefachim wide, for this is fixed.

Shulchan Aruch (3): If poles come out of the four corners of the bed one may not spread a sheet over them and sleep under it, even if they are less than 10.

Beis Yosef (DH ha'Etzim): Rashi forbids a sheet on Kinofos even if it is for Noy. It is forbidden even if it is far from the Sechach, so the Pesul of Pasul Sechach does not apply.

Shulchan Aruch (ibid.): If two poles come out of the middle of the bed, one at the head and one at the foot, and they are joined by poles, one may spread a sheet over them and sleep under it. This is because it is not a roof. This is if they are less than 10 tall. Some permit even if they are 10.

Gra (DH v'Yesh): The first opinion agrees that a sloped roof is not a roof. It forbids mid'Rabanan.

Sha'ar ha'Tziyon (11): Here, the 10 Tefachim are measured from the bed because the poles rest on the bed, unlike a Kilah.