005 - הִלְכוֹת קִדּוּשׁ הַחֹדֶשׁ פֵּרֶק ה

The Rambam begins by clarifying that everything we've discussed so far regarding the establishment of Rosh Chodesh—the new month—based on ראיה—sighting of the new moon, as well as the intercalation of the year (adding a leap month) due to either the time or necessity, can only be done by the Sanhedrin in Eretz Yisroel or by a Beis Din that has סמיכה—rabbinic ordination, in Eretz Yisroel, who were given permission by the Sanhedrin.

The source for this is the verse said to Moshe and Aharon: החודש הזה לכם—"This month shall be for you" (Shemos 12:2). The Rambam explains, based on the tradition passed down from Moshe Rabbeinu, that the phrase לכם—"for you"—means that this testimony, the authority to sanctify the new month, is given to you and to those who stand in your place after you. In other words, the power to establish the calendar is given to the Sanhedrin and their successors in Eretz Yisroel.

However, when there is no Sanhedrin in Eretz Yisroel, we do not establish new months or intercalate years based on sighting or need. Instead, we rely solely on the calculation—the חשבון—that we use today. This is the system we follow in our times, where there is no Sanhedrin.

The Rambam continues and states that this is a halacha leMoshe miSinai—a law given to Moshe at Sinai. When there is a Sanhedrin, the months are established based on ראיה—the sighting of the new moon. When there is no Sanhedrin, the months are established based on the חשבון—the calculation that we use today.

He points out that in such times, there is no need to rely on actual sightings of the moon. However, there are occasional situations where the day set by calculation coincides with the day of the sighting, or it may be a day before or after the sighting. The Rambam notes that when Rosh Chodesh falls after the sighting, this is considered unusual—פלא הוא—it's a wonder, something out of the ordinary. This phenomenon is particularly found in lands that are to the west of Eretz Yisroel, where the calculation and the actual sighting may not always align.

The Rambam now addresses the historical transition to the calculated calendar. He asks: From when did all of Israel begin to rely on this calculation?

He explains that this began at the end of the era of the sages of the Talmud, when Eretz Yisroel was destroyed and there was no longer a permanent Beis Din there. Up until that point, during the times of the sages of the Mishnah and even through the period of the sages of the Talmud—up to the days of Abaye and Rava—they relied on the establishment of the new month in Eretz Yisroel by the Sanhedrin.

The Rambam describes what happened when the Sanhedrin was functioning and the months were established by ראיה—the sighting of the new moon. In those times, the Jews living in Eretz Yisroel, as well as all the places that the שלוחי תשרי—the messengers sent out in Tishrei—could reach, would observe only one day of Yom Tov.

He explains that the messengers had a limited amount of time to travel and inform people when Rosh Chodesh was established. For Tishrei, they had only ten days to reach as many places as possible, because during that month, there are several days when travel is not possible due to Yom Kippur and Shabbos. This ten-day window was enough to cover all of Eretz Yisroel and some nearby areas outside of Eretz Yisroel.

However, in more distant places where the messengers could not reach within those ten days, people would observe two days of Yom Tov out of doubt—מספק—because they did not know on which day the Sanhedrin in Eretz Yisroel had established Rosh Chodesh. This uncertainty affected the observance of festivals like Pesach and Sukkos as well, since their dates depend on knowing the correct day of Rosh Chodesh.

In our times, when there is no Sanhedrin and the Beis Din of Eretz Yisroel establishes the calendar based on calculation, the Rambam says that logically, everyone everywhere should observe only one day of Yom Tov—even those in faraway places outside of Eretz Yisroel. This is because everyone now relies on the same calculation, and we all know exactly when Rosh Chodesh and the festivals fall.

However, the Sages instituted that we should continue to follow the custom of our ancestors—מנהג אבותיהם שבידיהם—and keep two days of Yom Tov in the Diaspora. The reason for this is a concern that, if there were ever a time when persecution or other circumstances would force us to revert to the old system, we would already be accustomed to keeping two days. Thus, the two-day observance is a rabbinic enactment to preserve tradition and preparedness for any future changes.

Therefore, the Rambam explains, any place where the שלוחי תשרי—the messengers of Tishrei—did not reach, even in the times when they would go out, should observe two days of Yom Tov, even nowadays. This is the same practice as when the months were established by sighting. In Eretz Yisroel, however, the custom has always been to observe only one day, and they never observed two days.

As a result, the second day of Yom Tov that we observe in the Diaspora today is not because of any doubt about the calendar. Rather, it is a rabbinic enactment—מדברי סופרים—instituted by the Sages to maintain the tradition.

The Rambam now discusses the unique case of Rosh Hashanah. Even when the months were established by ראיה—sighting, most of the Jews in Eretz Yisroel would observe Rosh Hashanah for two days out of doubt. This was because they did not know on which day the Beis Din had sanctified the new month, since the messengers could not travel on Yom Tov to inform them.

Sometimes, even in Yerushalayim itself, there was uncertainty. If the witnesses to the new moon arrived late, people would be unsure whether the thirtieth day or the thirty-first day was sanctified as Rosh Chodesh. As a result, they would observe both days as holy, refraining from work and treating both as Rosh Hashanah.

This practice became so established that even in Eretz Yisroel, Rosh Hashanah is now always observed for two days everywhere, even though the rest of the festivals are only one day. The second day of Rosh Hashanah is not due to doubt, but rather is a rabbinic institution—a decree of the Sages.

The Rambam now points out an interesting historical fact about ירושלים—Jerusalem itself, which was the very location of the בית דין—the court that sanctified the new month. Even there, in the heart of the process, there were many times when they would keep יום טוב של ראש השנה שני ימים טובים—two days of Rosh Hashanah.

Why was this? If the witnesses who were supposed to testify about the new moon did not arrive on the thirtieth day, the people would still treat that day as holy, waiting for the witnesses. They would keep it as קודש—a festival, and then the next day as well. So, both the day they were waiting for the witnesses and the following day were observed as Rosh Hashanah.

This practice was so established that, even in the time when the months were set by actual sighting, and even in Jerusalem itself, they would sometimes keep two days. Because of this, the Sages instituted that even the people of ארץ ישראל—the Land of Israel—should always keep two days of Rosh Hashanah, even in later generations when the calendar is set by calculation.

So, nowadays, even though we have a fixed calendar and know exactly when Rosh Hashanah is, the custom remains to keep two days everywhere, including in Eretz Yisroel. The Rambam concludes: from here you learn that even the second day of Rosh Hashanah in our times is not because of doubt, but is a Rabbinic enactment—מדברי סופרים—from the words of the Sages.

The Rambam now clarifies that the rule of keeping one day of Yom Tov is not simply determined by how close a place is to Jerusalem. He gives an example: even if a place is only a five-day journey from Jerusalem, and it is certain that the Shluchim—the messengers—could have reached there, we do not automatically say that the people of that place should keep only one day.

Why not? Because who says the messengers actually went there? Maybe there were no Jews living in that area at the time, so the messengers had no reason to go. Or perhaps, after the calendar was fixed by calculation, Jews later settled there, but since there was no tradition of keeping one day, they must keep two days.

There could also be other reasons why the messengers did not reach a certain place, even if it was close. For example, there might have been war or danger on the roads, as was the case between Yehuda and the Galil in the days of the Sages of the Mishnah. Or perhaps hostile non-Jews prevented the messengers from passing through.

The main point is that proximity alone does not determine the custom. It depends on whether the messengers actually went there and whether there was a Jewish community to receive them. If not, the place follows the general rule and keeps two days.

The Rambam further illustrates that the rule is not based on distance by pointing to Egypt. If the matter depended on proximity, then all the Jews in Egypt would keep only one day of Yom Tov, since it is possible for the messengers to reach Egypt within eight days by way of Ashkelon. The same is true for most of Syria, which is also within the ten-day travel limit.

However, in practice, these places did not always keep one day. This shows that the determining factor is not simply how close the place is to Jerusalem. Rather, it depends on the established tradition and whether the messengers actually went there. If there was no tradition of keeping one day, or if the messengers did not go, the place keeps two days, regardless of distance.

The Rambam summarizes the main principle: any place that is more than a ten-day journey from Jerusalem always keeps two days of Yom Tov, as the messengers could not reach there within the necessary time. This was the established custom from earlier generations.

For places within a ten-day journey, it depends. If the location is in Eretz Yisroel and was inhabited by Jews at the time of the Second Conquest—such as Usha, Shfaram, Lud, Yavneh, Nov, Tiberias, and similar cities—then they keep only one day, because the messengers could reach them and there was a tradition of doing so.

But if the place is in Syria—like Tzor, Damascus, Ashkelon—or outside of Eretz Yisroel, such as Egypt, Ammon, Moav, and similar areas, then the custom depends on the tradition of the local community. If their ancestors kept one day, they continue with one day; if two days, then two days. The key is to follow the established custom of the community.

The Rambam addresses what to do in places within ten days of Jerusalem, but which are in Syria or outside of Eretz Yisroel and have no established custom. Or, if it is a new city built in a previously uninhabited area of Eretz Yisroel, or a place where Jews have only recently settled—what is the rule there?

In such cases, since there is no established tradition, the people follow the practice of the majority of the Jewish world and keep two days of Yom Tov. The Rambam repeats that every second day of Yom Tov is a Rabbinic enactment—מדברי סופרים—even the second day of Rosh Hashanah, which everyone keeps nowadays.

The Rambam now explains the meaning of our current calendar calculations. When we say in each city that today is Rosh Chodesh or that Yom Tov falls on a certain day, it is not because we are establishing the date ourselves based on our own calculation.

Rather, we are not authorized to establish leap years or sanctify months outside of Eretz Yisroel. Instead, we rely on the calculation and the establishment done by the Jews in Eretz Yisroel. Our calculations are only to reveal and publicize which day was set as Rosh Chodesh or Yom Tov by the people of Eretz Yisroel.

In other words, we calculate in order to know which day was established in Eretz Yisroel, and that is the day we observe. The sanctity of the day comes from their establishment, not from our own calculation.