QUESTION: The Gemara records a dispute between Rav and Rav Asi with regard to whether one must read the Megilah with at least ten people ("b'Asarah") or whether one may read the Megilah by oneself ("b'Yachid"). Rav says that when one reads the Megilah "b'Zemano," on its proper day (the fourteenth of Adar), he may read it b'Yachid. Rav Asi says that he must read it b'Asarah, with ten people, whether b'Zemano or not b'Zemano.
The Gemara says that Rav was stringent and conducted himself like Rav Asi. He gathered ten people for the reading of the Megilah b'Zemano.
When RASHI comments on Rav's original statement, he explains why the Megilah may be read b'Yachid when it is read b'Zemano. Rashi says that since, b'Zemano, everyone else is reading the Megilah, there is Pirsumei Nisa even when an individual reads it by himself at home. In contrast, when the Megilah is not read b'Zemano and not everyone is reading the Megilah (but only the villagers who are entitled to read it on the Yom ha'Kenisah), it must be read with ten people in order to achieve Pirsumei Nisa.
According to Rashi, when Purim occurs on Shabbos everyone reads the Megilah on Erev Shabbos. Consequently, it should be considered b'Zemano and an individual should be permitted to read it b'Yachid! What is the Gemara's question on Rav from his statement that if Purim occurs on Shabbos, the Megilah may be read b'Yachid on Erev Shabbos? According to Rashi's explanation, Rav's second statement does not contradict Rav's first statement. On the contrary, it supports his first statement.
What is the Gemara's question on Rav according to Rashi's logic? (TUREI EVEN and others)
(a) The SEFAS EMES and CHIDUSHIM U'VI'URIM explain that Rashi understands the Gemara differently. Rashi learns that when the Gemara says that Rav took into consideration Rav Asi's opinion and read the Megilah b'Zemano with ten people, it does not mean that he merely conducted himself stringently. Rather, it means that he changed his mind and adopted the view of Rav Asi.
Accordingly, the Gemara questions whether Rav really changed his mind. The Gemara quotes a second statement of Rav which clearly shows that he did not change his mind. Rav's second statement -- that when Purim occurs on Shabbos and the Megilah is read on Erev Shabbos, an individual may read it b'Yachid -- shows that he maintains that b'Zemano the Megilah may be read b'Yachid (since everyone is reading it on that day and there is Pirsumei Nisa).
(According to this explanation, Rashi's text must have had the words "u'Mi Avad Rav Hachi" -- "Did Rav do this" (i.e. conduct himself in accordance with Rav Asi), instead of "u'Mi Amar Rav Hachi" -- "Did Rav say this" (i.e. his original statement).)
According to this understanding of the Gemara, the Halachah should follow the view of Rav Asi, because Rav retracted his opinion and conducted himself like Rav Asi. Thus, even b'Zemano the Megilah must be read with ten people.
(b) Other Rishonim (such as the RAN) disagree with Rashi and explain that even when Purim falls on Shabbos and the Megilah is read on Erev Shabbos, it is considered not b'Zemano, and thus the Gemara is asking a question on Rav's original statement. According to these Rishonim, what is Rav's logic that the Megilah may be read b'Yachid when it is read b'Zemano?
The TUREI EVEN explains that when Purim falls on Shabbos and the reading of the Megilah is moved to Erev Shabbos, the Mitzvah of Simchah (the Se'udah) is observed on Purim day itself, on Shabbos.
Normally, when Simchah is observed on Purim day, on the fourteenth of Adar, that celebration itself causes Pirsumei Nisa. Hence, there is Pirsumei Nisa even when an individual reads the Megilah by himself. However, when Simchah is observed on a day other than the day on which the Megilah is read (such as when Purim falls on Shabbos), there is no Pirsumei Nisa unless the Megilah is read publicly, with at least ten people.
2) HALACHAH: "PURIM MESHULASH" -- PURIM WHICH FALLS ON SHABBOS
OPINIONS: The Gemara says that when the Megilah is read earlier than the actual day of Purim (such as by the residents of small villages on the Yom ha'Kenisah), the Mitzvah of Simchah (the Se'udah) is still observed on the fourteenth of Adar.
When is the Mitzvah of Simchah observed when Purim falls on Shabbos? Although the Mishnah says that the Megilah is read the day before, on Erev Shabbos, it does not mention when the other Mitzvos of Purim are observed.
(For most cities, this question has no practical relevance. The fourteenth of Adar can never occur on Shabbos according to the fixed calendar which we follow. However, in walled cities (such as Yerushalayim) which observe Purim on the fifteenth of Adar, this question is relevant, because the fifteenth of Adar can occur on Shabbos (such as in the years 5761, 5765, 5768, 5781, and 5785, or 2001, 2005, 2008, 2021, and 2025).)
(a) The RIF cites the Tosefta which adds to the Mishnah. The Mishnah here mentions that certain Mitzvos which apply on specific days of the year are fulfilled on an earlier day when their respective day falls on Shabbos, and they are not deferred to after Shabbos. The Tosefta says that one such Mitzvah is the Se'udah of Purim.
The RAN cites the Yerushalmi which says that the Se'udah of Purim cannot be observed on Shabbos because the Simchah of Se'udas Purim must not be mixed with any other Simchah. The Se'udah must be on a day on which there is no Simchah other than the Simchah of Purim. Therefore, the Yerushalmi says that the Se'udah of Purim should be conducted after Shabbos, on the sixteenth of Adar.
The Yerushalmi's ruling is difficult to understand. The Gemara (2a) derives from the verse, "v'Lo Ya'avor" (Esther 9:27), that although Purim may be observed earlier than its designated date, it may not be observed after the fifteenth of Adar. The verse refers to the Mitzvos of Purim ("Asiyah") such as Mishlo'ach Manos, Matanos l'Evyonim, and the Se'udah. Why does the Yerushalmi say that the Se'udah may be celebrated on Sunday, the sixteenth of Adar?
The Ran explains that the verse of "v'Lo Ya'avor" does not refer to the Se'udah and the other Mitzvos of Purim. Rather, the verse refers to the words from which the Gemara (2a) derives that the Megilah may be read on two days other than the fourteenth and the fifteenth of Adar. When the Megilah is read early (such as by the residents of small villages on the Yom ha'Kenisah), only the reading of the Megilah is performed on an earlier day, but not the Se'udah. Hence, "v'Lo Ya'avor" applies only with regard to the reading of the Megilah.
(b) The RAN and RITVA cite the RE'AH who explains the Yerushalmi differently. As mentioned above, the Yerushalmi cannot mean that the Se'udah is observed on the sixteenth of Adar, because the verse says, "v'Lo Ya'avor." Rather, the Yerushalmi means that the Se'udah of Purim is delayed until after the reading of the Megilah of the people who live in small villages. That is, the villagers do not conduct the Se'udah of Purim on the same day as they read the Megilah. Rather, they conduct the Se'udah later, on the fourteenth of Adar, the date on which everyone celebrates the Simchah of Purim.
According to the Re'ah, since the Mitzvah of Simchah is observed after the Megilah has been read, when Purim falls on Shabbos the Se'udah is conducted on Erev Shabbos after the Megilah has been read.
The Ran rejects this explanation because it is not consistent with the words of the Yerushalmi.
(c) The MAHARALBACH (#32) writes that the Gemara here disagrees with the Yerushalmi and maintains that the Simchah of Purim may be celebrated on Shabbos, because Simchah is always celebrated in its proper time. He proves this from the Gemara later (30a) which implies that when Purim falls on Shabbos, the Se'udah of Purim is held on Shabbos.
HALACHAH: The SHULCHAN ARUCH (OC 688:7) records the opinion of the RAN who rules that the Se'udah is held on Sunday. The Megilah is read and Matanos l'Evyonim are distributed on Friday. "Al ha'Nisim" and the Torah reading of Purim are said on Shabbos, the fifteenth of Adar (BEIS YOSEF). Accordingly, when Purim falls on Shabbos it is called "Purim Meshulash," since it spans three days.
The Acharonim discuss at length whether the Mitzvah of Mishlo'ach Manos should be performed on Sunday because it is considered part of the Se'udah, or on Shabbos because that is the actual day of Purim. Because of the doubt, the common practice is to be stringent and to perform the Mitzvah of Mishlo'ach Manos on both Shabbos and Sunday.
3) THE REASON FOR DELAYING "ZEMAN ATZEI KOHANIM VEHA'AM"
QUESTION: The Mishnah lists the events which are deferred until the following day when their respective dates fall on Shabbos -- "Zeman Atzei Kohanim veha'Am, Tish'ah b'Av, Chagigah, and Hakhel."
The Gemara explains that the reason why Tish'ah b'Av is deferred to after Shabbos and is not observed on the day before Shabbos is because it is a day of mourning and tragedy. It is appropriate to delay such a day and not to observe it earlier. The Gemara also explains why Chagigah and Hakhel are delayed a day and are not observed on the day before Shabbos: the time of their obligation has not yet arrived before Shabbos.
The Gemara, however, gives no reason for why Zeman Atzei Kohanim is delayed. The days of "Zeman Atzei Kohanim veha'Am" are days observed as Yom Tov by the families who donated the wood for burning sacrifices upon the Mizbe'ach in the times of the second Beis ha'Mikdash. In recognition of their Mitzvah, those families and their descendants were granted the privilege of bringing wood to the Beis ha'Mikdash on certain days every year. (They could not bring wood on Shabbos because the Korbanos which they offered at the time they donated the wood (see Background to the Daf) could not be offered on Shabbos.)
Why does the Gemara not discuss this event?
ANSWER: The RAN and RASHI on the Rif explain that there is no need to discuss Zeman Atzei Kohanim because the reason it is delayed is obvious. Each family brought enough wood to last until the next family brought its contribution of wood. If the new family's day occurred on Shabbos, that family could not bring wood on the day before Shabbos because the previous family was granted the privilege of bringing wood on that day. The fact that the second family's day fell on Shabbos did not entitle that family to infringe on the first family's day.
In contrast, the previous family was not infringing on the next family's day when it brought the wood for Shabbos, because had it not brought the wood for Shabbos, no one would have brought it. Therefore, the new family brought the wood only on Sunday, after Shabbos.

5b----------------------------------------5b

4) AGADAH: THE PROHIBITION OF MELACHAH ON PURIM
The Gemara says that the Chachamim originally enacted that Purim be observed as a Yom Tov even with regard to the prohibition of Melachah. Subsequently, however, the people did not accept this enactment. Therefore, one is permitted to do Melachah on Purim.
RAV YITZCHAK HUTNER zt'l (in Pachad Yitzchak) explains why the people did not accept the prohibition of Melachah on Purim. He cites the VILNA GA'ON who inquires about the nature of the two festivals instituted by the Rabanan, Chanukah and Purim. Why is there a Mitzvah to be especially happy (Marbim b'Simchah) and to make a Se'udah on Purim, but there is no obligation to recite Hallel on Purim (Megilah 14a)? Conversely, why on Chanukah is there an obligation to recite Hallel, but there is no obligation to make a Se'udah?
The Vilna Ga'on explains as follows. There are eighteen days of Yom Tov mid'Oraisa in the year: seven days of Pesach, seven days of Sukos, Shemini Atzeres, Shavuos, Rosh Hashanah, and Yom Kippur. On eight of those days Hallel (or the full Hallel) is not recited: the last six days of Pesach, Rosh Hashanah, and Yom Kippur.
The Chachamim established Yamim Tovim d'Rabanan to make up for those eight days mid'Oraisa on which there is no Hallel. They instituted the eight days of Chanukah, on which Hallel is recited, to make up for the Yamim Tovim d'Oraisa on which Hallel is not recited. However, since those eight Yamim Tovim d'Oraisa have an obligation of Simchah and Se'udah, the Chachamim did not need to enact an obligation of Simchah and Se'udah on Chanukah. Hence, they enacted an obligation to say Hallel without an obligation to have a Se'udah.
Besides the eight days d'Oraisa on which Hallel is not recited, one of the Yamim Tovim d'Oraisa lacks a Se'udah, an expression of Simchah through feasting: Yom Kippur. The Chachamim compensated for that missing Se'udah by instituting the festival of Purim. Yom Kippur is the day of the greatest Simchah (Ta'anis 26b), and thus the Chachamim established that the Yom Tov of Purim have more Simchah than any other Yom Tov, since it corresponds to Yom Kippur. Moreover, it was on Yom Kippur that Hash-m forgave the Jewish people for the sin of the Golden Calf and gave them the second set of Luchos. Similarly, on Purim, the Jewish people re-accepted the Torah ("Kiyemu v'Kiblu"), and thus it is an appropriate day to make up for the Simchah of Yom Kippur.
Rav Hutner suggests that this explains why there is no prohibition of Melachah on Purim. There was no reason for the Chachamim to enact a prohibition of Melachah because all of the Yamim Tovim d'Oraisa have a prohibition of Melachah and thus no prohibition of Melachah is missing (such that it needs to be compensated for on Purim).
Rav Hutner does not explain why the people did observe the prohibition of Melachah the first year that Purim was instituted. Perhaps during the first year, the people celebrated not only for the miracle that occurred, but for the personal salvation that they experienced. One who celebrates a personal salvation offers a Korban Todah in the Beis ha'Mikdash. Even though there was no offering of Korbanos yet at the time of Purim because the Beis ha'Mikdash had not yet been rebuilt, the people wanted to conduct themselves in the way in which one who brings a Korban Todah acts. One who brings a personal Korban treats that day as a Yom Tov and does not do Melachah (Tosfos to Pesachim 50a). Therefore, the people in the first year that the festival of Purim was established did not do Melachah on Purim! (M. KORNFELD)