Halakhah su Esodo 13:10

The commandment of sanctifying the new month To sanctify months and intercalate [months into] years in the court [whose members are the] great in wisdom and ordained in the Land of Israel, and to establish the year's holidays according to that sanctification; as it is stated (Exodus 12:2), "This month shall be to you the first of months." This means, when you see the renewal of the moon, establish for yourselves the new month - or even if you do not see it, since it is appropriate for [the moon] to appear according to the accepted calculation. Likewise, this commandment includes the commandment of intercalation, since the basis of the commandment to sanctify the month is for Israel to observe God's holidays at their appointed times. And the commandment of intercalation has the same basis. However, beyond this verse are more Torah passages concerning the commandment of intercalation, and that is what is written (Exodus 13:10), "You shall observe this commandment in its proper time"; and likewise, "Observe the month of Spring" (Deuteronomy 16:1).

The content of the commandment is that two Jews fit to testify come before the court and testify before them that they saw the renewed moon. [The judges then] establish the new month on the basis of their [testimony] and say, "Today has been sanctified." The reason why this commandment applies only with ordained judges is because it came with the explanation [of the verse], "This month shall be for you" - great [in Torah] and ordained, like you (Rosh Hashanah 22a), since it was said to Moshe and Aharon. This matter was further expounded, as it is juxtaposed to "speak to the entire congregation of the children of Israel," meaning that they who sanctify the month must have the assent of all Israel, meaning the wisest men of Israel, such as the Great Court (the Sanhedrin). And so [too] any great sage in Israel who was ordained in the Land of Israel. And since ordination is no longer practiced, as is known, [the sage] has permission to perform this commandment even outside the Land of Israel, so long as there is no one of his stature in the Land of Israel. And so we find that Chananiah son of Rabbi Yehoshua's brother, and Akiva ben Yosef did so in this regard (Berakhot 23a). But without these conditions, no one of Israel is permitted to establish the months or intercalate. And perhaps you will ask, "If so, how do we conduct ourselves today, when we lack ordained sages?" Know that so have we received it; since Rabbi Hillel the Prince, son of Rabbi Yehudah the Prince, who was the greatest of his generation and ordained in the Land of Israel - he was the sage who fixed for us the calculation of intercalation, sanctified future months, and intercalated future [months into] years until the coming of Eliyahu, and it is upon this that we rely today. That which we have said all follows the opinion of Rambam. However, Ramban (in the Sefer HaMitzvot LaRambam, Mitzvot Ase 153), considers the sanctification of the month as one commandment and intercalation a separate commandment. His proofs (for dividing these into two separate commandments are) in his Book of Commandments. And so [too] the Ba'al Halakhot (considers these separate commandments). And the verse that teaches about the commandment of intercalation, that is, that we calculate the seasons in order to make the holidays in their (proper,) established times, is "You shall observe this commandment in its proper time," (Exodus 13:10) and so, "Observe the month of Spring," (Deuteronomy 16:1) as we have written.

The laws of the commandment - for example, interrogating [those who offer] testimony concerning the new month; instilling fear in the witnesses on occasion; the law concerning circumstances under which the Shabbat may be desecrated for this testimony; for what [considerations] we do or do not intercalate; which month they would intercalate, i.e. Adar, as they, may their memory be blessed, expounded, "'You shall observe this commandment in its proper time' (Exodus 13:10), this teaches that we only intercalate at the time near the holiday"; and they, may their memory be blessed, further expounded on this verse, "From where do we know that we only intercalate the month during daytime? [We learn this from the] verse, [which] states, 'from year to year' (yamim yemima, literally from day to day) (Sanhedrin 10b); and they, may their memory be blessed, further expounded, "'For the months of the year' (Exodus 12:2) - it is months you calculate towards the year, not days" (Megillah 5a); furthermore did they say on this matter, "'A month of days' (Numbers 11:20), it is days you calculate towards the month, not hours" (Megillah 5a); and the rest of its details - are [all] elucidated in Tractate Rosh Hashanah, and in the first chapter of Sanhedrin, and similarly in Berakhot (see Mishneh Torah, Laws of Sanctification of the New Month 1).

Judah the Persian¹⁹ Mentioned by Ibn Ezra in his Commentary to the Pentateuch and elsewhere. Nothing is known of this scholar. (See Encyclopedia Judaica, second edition, vol. 11, p. 505.) said that the years used by Israel were solar years, because he found the festivals were on fixed dates: Passover when the barley ripens (Exodus 34:18), Pentacost at reaping time (ibid. 34:22), and Tabernacles at harvest time (Deuteronomy 16:13). However, what can be done since Moses did not specify the length of a year?²⁰ Since the Bible does not specify the exact length of a solar year, the Karites are left with the matter being undecided. This will also affect determination of the festivals. Also, how will he explain the use of the Hebrew term “hodesh” (new) for “month,” for what is renewed relative to the sun? The uncircumcised (Christians), because their years are solar years and they found that a full year contains twelve lunations, divided the days of the year into twelve parts, for this number is closest to the number of lunar months. The result is that some months are 30 days and some months are 31 days.²¹ Here Ibn Ezra accounts for the division of a year into twelve parts, even if one uses a solar calendar. However, the term “hodesh” would not be appropriate for such solar months.

That is that He commanded us to sanctify (proclaim) the months (in other versions, and to calculate the months) and years. And that is the commandment of sanctifying the month. And that is His, may He be exalted, saying, "This month shall mark for you the beginning of the months" (Exodus 12:2). And the explanation (Rosh Hashanah 22a) comes [and tells us] that "this testimony is given over to them" - meaning that this commandment is not given over to each and every individual, like the Shabbat of creation, towards which every individual counts six days and rests on the seventh. [Here, it is not] that when each and every individual sees the [new] moon, he determines that today is Rosh Chodesh (the first of the month), or that he should count some Torah matter and establish the new month or look into the lateness of the Spring - or something else that is fitting to observe - and add a month. Rather, this commandment is always only done by the High Court, and only in the Land of Israel. And the sighting [of the new moon] has therefore been annulled for us today with the absence of the High Court, just like the offering of sacrifices has been annulled with the absence of the Temple. And the heretics called Karaites have referred to this and erred about it. And this is a principle that even some of the rabbis did not concede and followed them into the darkness and the shade. You should know that the calculation that we count with today, through which we know Rosh Chodesh and the holidays, is impossible to do outside of the Land. However in the absence of sages in the Land of Israel, it is possible for a court that was ordained in the Land of Israel to intercalate years and determine months outside of the Land, like Rabbi Akiva did - as is explained in the Talmud (Berakhot 63a) - yet there is a great and strong question about this. And it is known that the Great Court, however, was in the Land of Israel; and that they were the ones that determined the months and intercalated the years in ways that were passed on to them, [doing so] in their gathering together. And this is one of the great principles of the faith - only those that have a deeper knowledge know it and see it in its place. And that is that that which we count today outside of the Land with the work of intercalation that is in our hands - and say that this day is Rosh Chodesh and that day is a holiday - is not because we have determined the holiday from our [own] calculation in any way. Rather, it is because the Great Court in the Land of Israel had already determined that this day is Rosh Chodesh or a holiday. And since they said that today is Rosh Chodesh or a holiday, it is [actually] Rosh Chodesh or a holiday - whether this action of theirs was through calculation or sighting - as appears in the explanation (Rosh Hashanah 25a), "'These are the set times of the Lord [...] which you shall proclaim as sacred occasions' (Leviticus 23:4); I have no other set times besides these" - meaning to say, the ones that they say are the sacred times, even under duress, even in error, even inadvertently - as it appears in the tradition. And we indeed consider the day determined by them - meaning the inhabitants of the Land of Israel - to be Rosh Chodesh. As it is upon [their] work itself that we count and determine [it] - not upon sighting; and it is upon their calculation that we rely, and not upon our [own] calculation. Rather our calculation is just an exposition of the matter. And understand this. And I will explain to you further. If we were to assume, by way of illustration, that the [Jewish] residents of the Land of Israel disappeared from the Land of Israel - God forbid that God would do this, since He promised that He would not erase the traces of the nation [there] totally - and that there would not be a court there, nor a court outside the Land of Israel that was ordained there. [In such a case,] this calculation of ours would surely not help us at all in any way. For we may only calculate months and intercalate years outside the Land of Israel according to the conditions mentioned, as we have explained - 'for out of Zion comes forth Torah.' And when someone with a complete intellect examines the [related] statements of the Talmud with this approach, everything that we said will become clear, without a doubt. And note that there were hints that appear in Scripture that indicate the principles of this work upon which we should rely to know Rosh Chodesh and the intercalation of years. Among them is His saying, "You shall keep this ordinance at its set time from year to year" (Exodus 13:10). They said (Mekhilta DeRabbi Shimon Bar Yochai 13:9), "It teaches that we only intercalate the year during the period that is proximate to the sacred occasion (Pesach)." And they said [further], "From where [do we know] that we only sanctify the month during the day? [Hence] we learn to say, 'from year to year (literally, from day to day).'" And they [also] said (Megillah 5a), "You calculate months for years, but you do not calculate days for years." This indeed indicates that the addition in this is in fact a full month. And they said [further], "'A month of days' - you count the days of a month, and you do not count the hours of a day." And His saying, "Observe the month of Spring" (Deuteronomy 16:1), indicates that it is fitting that we preserve the seasons of the year in our years, and that is why it is [also] solar. And the regulations of this commandment have already all been completely explained in the first chapter of Sanhedrin, in Tractate Rosh Hashanah and in Berakhot. (See Parashat Bo; Mishneh Torah, Sanctification of the New Month 1.)

And he first places that of the arm and afterwards that of the head; and when he removes them, he removes that of the head first. And [also] that which they said (Berakhot 9b, (Mishneh Torah, Laws of Tefillin, Mezuzah and the Torah Scroll 4:10) that the time of tefillin during the day is from when one can see his friend until the sun sets, as it is stated (Exodus 13:10), "You shall observe this statute in its proper time from day to day" - and "this statute" is the commandment of tefillin. And Shabbat and holidays - and the same is true of the intermediate festival days - are not a time for the placing of tefillin, as it is stated about them (Exodus 13:16), "And it shall be a sign." And Shabbat days and holidays are a sign themselves, and we do not need another sign.