1) THE GEDOLEI HA'DOR GRAZED THEIR ANIMALS DURING SUKOS
QUESTION: Rav Yosef rules like Rebbi Yochanan, who said that on the eighth day of Sukos outside of Eretz Yisrael, one should sit in the Sukah but not recite the blessing of "Leishev ba'Sukah." In Chutz la'Aretz, there is a doubt whether the eighth day is the seventh day of the festival and thus part of Sukos, or the eighth day (Shemini Atzeres) and separate from Sukos.
Rav Yosef rules like Rebbi Yochanan because "Rav Huna bar Bizna and all of the Gedolei ha'Dor" entered a Sukah on the eighth day in Chutz la'Aretz, and they sat in the Sukah but did not recite a blessing. The Gemara asks that perhaps the reason why they did not recite the blessing was not because they ruled like Rebbi Yochanan, but because they had already recited the blessing on the first day of the festival and they followed the opinion (45b) that one recites the blessing for the Sukah only on the first day. The Gemara answers that this was the first time they had sat in the Sukah for the entire festival, because only now did they return from the fields. The only reason why they did not recite the blessing was because they ruled like Rebbi Yochanan.
RASHI writes, "I learned from my teachers that they came in from the fields where their animals were grazing, and they had not dwelled in a Sukah for all of the days of the festival." TOSFOS adds that they did not even have "shepherd huts" in the fields with which to fulfill the Mitzvah (as the Gemara earlier (8b) describes).
How can it be that these Gedolei ha'Dor, the great sages of the generation, exempted themselves from the Mitzvah of Sukah in order to take care of their animals?
ANSWERS:
(a) The SEFAS EMES and others explain that these Gedolei ha'Dor were not away from the Sukah for the entire festival as Rashi says. Rather, they left the Sukah momentarily to check on their animals in the fields. The Gemara (26a) says that watchmen are exempt from the Mitzvah of Sukah while they work, and the same exemption applies to those who guard flocks of animals. Since these Gedolei ha'Dor became momentarily exempt from the Mitzvah of Sukah, there was a Hefsek, an interruption, between the blessing they recited at the beginning of the festival and their return to the Sukah after their inspection of the animals. Therefore, their original blessing could not apply to their return to the Sukah, and they should have recited a new blessing upon their return to the Sukah on the eighth day. The only reason they did not recite a new blessing was because they ruled like Rebbi Yochanan.
(b) The ARUCH LA'NER (in BIKUREI YAKOV 640:24) explains that the Gedolei ha'Dor went out to the fields to learn Torah in isolation in order to enable themselves to achieve greater levels of holiness (see Zohar, Parshas Tetzaveh). Since they were totally immersed in the Mitzvah of learning Torah, they were exempt from the Mitzvah of Sukah (25a, 26a). (He adds that they returned to the city on Shemini Atzeres because they did not want Hash-m to hold back the rains on account of their presence in the fields and exposure to the elements.)
(c) RAV REUVEN MARGOLIYOS (in NEFESH CHAYAH 640:8) suggests that they did not go out to the fields specifically to watch their animals. Rather, it was a time of persecution against the Jews in Pumbedisa (the city of Rav Huna bar Bizna), and they were forced to flee from the authorities.
(d) The YOSEF DA'AS cites RAV TZVI PESACH FRANK (in HAR TZVI) who writes in the name of RAV CHAIM BERLIN (see also HE'OROS B'MASECHES SUKAH) that the Gemara should read "m'Ifra Asu" instead of "m'Efer Asu." "Ifra" refers to "Ifra Hurmiz," the mother of the king of Persia, Shevor Malka (King Shapur II, 309-379 CE; Bava Basra 10b). The Gedolei ha'Dor were involved in negotiations with the ruler on behalf of the Jewish people, and therefore they were exempt from the Mitzvah of Sukah.
(e) The OR SAME'ACH (Hilchos Sukah 6:13) proposes an ingenuous explanation. The Gemara in Pesachim (52a) states that although it is necessary to observe two days of Yom Tov in places where the people are not expert in determining the new month (such as in Chutz la'Aretz), Talmidei Chachamim who know how to calculate the new month may observe only one day of Yom Tov when they are in isolated, uninhabited areas, even in Chutz la'Aretz.
When the Gedolei ha'Dor went out to the fields in order to watch their animals, they certainly dwelled in a Sukah. However, since they were in an uninhabited area, they were not bound to observe two days of Yom Tov out of doubt (since they were all Talmidei Chachamim who knew how to calculate the new month). Therefore, on the first day of Sukos they recited the blessing for the Mitzvah of Sukah, and that blessing covered the rest of the days of Sukos (since they followed the opinion (45b) that one recites the blessing for the Sukah only on the first day).
However, when they returned to the city on the eighth day, they were obligated to sit in the Sukah, because they had to conduct themselves like the rest of the people of Chutz la'Aretz and treat the eighth day as a doubt. However, the blessing they had recited on the first day could not cover the Mitzvah on the eighth day, because when they recited the blessing, they recited it for the Mitzvah to sit in a Sukah for seven days, and not for the Mitzvah to sit in a Sukah for eight days. Had the Gedolei ha'Dor been in the city during the second day of Sukos, they would have been required to recite a blessing on the Sukah again, out of doubt that perhaps that day was really the first day of Sukos (and the previous day was Erev Sukos and not Sukos). The blessing they would have recited (out of doubt) on the second day would have exempted them from a blessing (out of doubt) on the eighth day.
However, since the Gedolei ha'Dor were not in the city on the second day of Sukos, they recited a blessing only on the first day of Sukos, and that blessing did not exempt them from a blessing on the eighth day (out of doubt), since, if the eighth day was Sukos, the blessing they recited on the first day was recited on Erev Sukos! They would have had to recite a new blessing upon sitting in the Sukah on the eighth day. The fact that they did not recite a new blessing when they sat in the Sukah on the eighth day showed that they ruled like Rebbi Yochanan.

OTHER D.A.F. RESOURCES
ON THIS DAF