Implied Question: It was the eleventh of Tishrei for the people of Babylon, and it was the tenth of Tishrei for the people of Eretz Yisrael since they had extended Elul by a day. (If so, how was it permitted for Levi to travel between cities on Yom Kippur?)

Answer #1: He must have arrived from inside the Techum, as it was Yom Kippur.

Answer #2: Alternatively, he arrived on Yom Kippur in Babylon close to nightfall, which was Erev Yom Kippur for the people of Eretz Yisrael.

Explanation: They asked him, "Can you testify for us?" This means that they wanted to forbid eating on the following day as well since it will be the real Yom Kippur (according to the second answer above). He told them, "I did not hear from the mouth of Beis Din that they said "Mekudash." In other words, Levi had left on the thirtieth day close enough to nightfall to know that the Beis Din in Eretz Yisrael did not have time to accept anymore testimony that day. He knew that they would only be Mekadesh the new year on the next day which would be the thirty first day (i.e. the first of Tishrei).

Explanation (cont.): However, he did not wait to travel the next day in order to hear that they were Mekadesh the next day. One cannot testify with certainty until they hear from Beis Din that the month is Mekudash, as stated later (21b), even though he knew with certainty that they would be Mekadesh the month the next day.

Question: How did he let them eat? It is certain that they would all be transgressing a prohibition for which one is liable to receive Kares!

Answer: The Mishnah says later (25a) that we see from the Pasuk, "That you will call them Mikrai Kodesh," that this is whether this is during the proper time or not. The Gemara says, "You" means whether Beis Din accidentally, on purpose, or mistakenly is Mekadesh the wrong day.

Implied Question: The Gemara in Chulin (101b) says regarding someone who mistakenly did not eat on Yom Kippur that he is exempt, as this is a decree. [It was a decree that year, as] Yom Kippur on that year was instituted to be on Shabbos (despite the fact that it really wasn't, see Gemara there at length). We see that we do not say it is treated like Yom Kippur, despite the derivation of "You" even on purpose. (Why doesn't it have the status of a regular Yom Kippur?)

Answer: The case in Chulin (ibid.) was when the month was instituted at the appropriate time, but because of the decree they were not able to make Yom Kippur on the tenth of Tishrei. They made it on Shabbos in order that they should not forget about Yom Kippur, and that it is supposed to be on the tenth of Tishrei. However, in our Gemara it was the tenth of Tishrei.

Implied Question: This is unlike the Gemara in Sanhedrin (12b) where Chizkiyah prayed that Hash-m should be merciful with him since the Pasuk states, "For they ate the Pesach when it was not stated etc." The Gemara explains that he only established a leap year on the thirtieth of Adar. This is forbidden, since the thirtieth could technically be Rosh Chodesh Nisan. We see that we do not say in this case, "You" even if you are accidental.

Answer: This is because it only applies to the thirtieth or thirty-first day when they establish one of them as Rosh Chodesh to make it less or to make it extended improperly, or if it is based on false testimony.

Explanation #1: [You should establish a leap year if] The Tekufah of Nisan falls on the sixteenth. We hold (Sanhedrin 13a) that the day the Tekufah starts is included in its amount of days. This means that the Tekufah of Teves, in this case, is until the sixteenth of Nisan but does not include it.

Explanation #1 (cont.): In such a case you should establish a leap year, since the Pasuk states, "Guard the summer month" which refers to the Tekufah of the summer. It is supposed to mainly be in Nisan, and if it starts after the fourteenth of Nisan it is considered "old" (not mainly in Nisan).

Explanation #1 (cont.): If they would see that the Tekufah of Nisan falls on the fifteenth we would not need to extend the year. Rather, we would extend Adar which would push aside the start of Nisan one day, causing the Tekufah to fall on the fourteenth. This is the explanation of Rashi. Our Gemara is according to Acheirim, as we say there that Acheirim are referring to the Tekufah of Nisan, and it quotes the derivation mentioned in our Gemara.

Question: There is a difficulty with the explanation of Rashi. In Sanhedrin (41b), the Gemara implies that the fifteenth of the month is still a main part of the month. This is as the Gemara there says, "Until when can one say the blessing over the new moon? Nehardei says until the fifteenth of the month."

Explanation #2: Therefore, one must explain that when the Gemara here says, "until the sixteenth" it means even if we would extend Adar.

Explanation #3: Alternatively, it means Tekufas Teves is until the sixteenth, including the sixteenth (unlike Rashi's understanding in a). Accordingly, if a year is going to have Tekufas Nisan fall on the seventeenth, even if one would extend Adar it would fall on the sixteenth, it would not be deemed that the month of Nisan is a summer month (as the sixteenth is deemed to belong to Tekufas Teves).

Implied Question: One should not ask, why don't we extend Adar and Shevat? (Why not? Won't this make the Tekufah earlier in Nisan without having to establish a leap year?)

Answer: The Mishnah says in Erchin (8b) that we do not make less than four full months a year and no more than eight full months a year. The Gemara there (9a) explains that we will not see extending more than eight in a leap year. However, the Gemara establishes that in a regular year we do not have more than seven full months.

Question: This is difficult. The Beraisa in Sanhedrin (11b) states that there are three indicators that we should establish a leap year. They are: Aviv (if the produce will not be ripe), the fruit (will not be ripe in time), and the Tekufah (will not fall out when it is supposed). If two of these signs apply, it causes us to establish a leap year. One reason alone does not make us establish a leap year. Rabban Shimon ben Gamliel there merely states, "Al ha'Tekufah." The Gemara there asks, "Is he saying they are happy about the reason of Tekufah or that this causes us to establish a leap year?" The Gemara there concludes in Teiku.

Answer: The Gemara there is referring to Tekufas Tishrei. Our Gemara is referring to Tekufas Nisan, which causes us to establish a leap year (without an additional reason).

Implied Question: This difference (Tishrei and Nisan) requires a reason, as both are derived from Pesukim. Why should one establish a leap year more than the other?

Explanation: Rashi explains that according to Torah law one may transgress Shabbos for all of them. However, the Rabbanan forbade this because establishing the festivals is not dependent on these months. We therefore do not care that much if they are full months or months are lacking due to witnesses testifying.

Question: This is difficult, as the Gemara quotes a Beraisa stating, "How do we know that we desecrate Shabbos for this? The Pasuk states, "These are the festivals of Hash-m." This Pasuk is referring to Nisan and Tishrei (when the festivals occur)!"

Answer: Even so, every Rosh Chodesh is included since it is called a festival, as stated in Pesachim (77a) regarding the pushing off of Shabbos and pushing aside impurity regarding sacrifices of Rosh Chodesh. The Gemara says that these need to be stated. I might think that the Pasuk does not state festival regarding these things (and therefore they should not push aside Shabbos or impurity). This is why we need to understand that Rosh Chodesh is also called a festival, as stated by Abaye.

Explanation: The Mishnah that states, "these are the months regarding which messengers go out" refers to after they hear from the mouth of Beis Din that these months have been sanctified. It is a reason, meaning that the importance of messengers needing to go out is why the witnesses desecrate Shabbos in order to testify.

Explanation (cont.): Rashi explains that in other months the desecration of Shabbos that would be done by witnesses would not cause messengers to hurry, as the messengers would not go out if it were Shabbos. If witnesses will not arrive on Shabbos the month will be a full month, and everyone will know that it will be sanctified the next day. The messengers will go out after nightfall and say the month was full.

Explanation (cont.): However, regarding Nisan and Tishrei, if the witnesses will not come and cause the month to be extended, the messengers will not go out until the next day, as Beis Din does not sanctify the month at night. This will cause the messengers to not be able to go out for at least an extra night, possibly more.

Question: Rashi's explanation is difficult, as he made the reason that witnesses can desecrate Shabbos dependent on the messengers going out. If the thirtieth day of Elul falls on Shabbos and the witnesses see the new moon, they must desecrate Shabbos (even without this reason). If they wait until Sunday, Hoshana Rabah would fall on Shabbos. This is indeed a reason to push aside Tishrei, as stated in Sukah (43a).

Answer: However, regarding Nisan we definitely need a reason (and therefore Rashi's reason is understandable regarding Nisan).

Answer: Rashi in the Mishnah explained that this is when the messengers go out, and therefore they are important months. This means that since the messengers go out in order to make people observe the festivals at the right time, it is fitting for witnesses to come testify even if they desecrate Shabbos by doing so in order for people to observe the festivals at the right time.

Answer (cont.): Rashi here also explains that the reason for the desecration of the witnesses in order to be Mekadesh the month in its proper time is as the Mishnah states, "and with them we fix the festivals." The Torah states, "that you will call them," implying they even go out on Shabbos. The Mishnah states that messengers go out to give a nicer reason, and to explain why there is a need to desecrate Shabbos. It is common to find things that are not the main reason for something, yet they help make a law understandable and nicer.

Proof: This is like what we learn in Sanhedrin (11a) that one does not establish a leap year due to the goats and sheep. However, they are used to help along establishing a leap year. How is this so? We are letting you know that the birds are soft etc. (In a letter requesting audience to establish a leap year these topics would be mentioned, even though they would not be the main reason to establish a leap year.)

Question: What is the reason of our Mishnah regarding Nisan and Tishrei that the messengers have to hear Beis Din say that the month is sanctified?

Question (cont.): It is understandable that if the moon was clearly seen on the twenty ninth or on the night of the thirtieth that the messengers would not go out even though Beis Din will certainly sanctify it the next day. This is because we suspect that Beis Din will change their mind and make it a leap month, and people will end up having the festivals on the wrong day. However, if they did not sanctify the month on the thirtieth, let the messengers go out on the thirty first day as it is impossible to push this aside more than the thirty first!

Answer: It is possible to say that they decreed this case because of the other cases, as regarding other months they can go in both cases at night.