Rosh Hashanah 2:7 - 2:8

ראש בית דין אומר מקודש – as it is written (Leviticus 23:44): “So Moses declared [to the Israelites] the set times of the LORD.” From here that the head of the Jewish court says, “Sanctified.”

וכל העם עונין אחריו – As it is written (Leviticus 23:2): “[Speak to the Israelite people and say to them: These are My fixed times,] the fixed times of the LORD, which you shall proclaim [as sacred occasions].” It is read as "אתם" /”them” – for it is written defectively without the letter “VAV.”

מקודש מקודש – Two times as it is written, “sacred occasions”/"מקראי קדש" – two occasions.

שנראה בזמנו – on the night of the thirtieth [of the previous month].

אם לא נראה בזמנו – and they establish Rosh Hodesh on the thirty-first [day].

אין מקדשין אותו – The sanctification of the month is not obligatory, as the Bible states (Leviticus 25:10): “And you shall hallow the fiftieth year…” Years you sanctify, as it is obligatory upon the Jewish court to say that the year is sanctified as the Jubilee year, but you do not sanctify months, for there is no obligation upon the Jewish court to state that the month is sanctified. But when it appears at the appropriate time, we sanctify it because it needs strengthening. And the Halakha is according to Rabbi Eleazar b’Rabbi Tzadok.

צורות לבנות – the measurement of the moon and to which side its horns incline.

קיבלן ר"ג – not because he thought that it was possible that the moon could be seen in the morning in the east at the start of sunrise, and on that day itself, it would be seen in the west with the setting of the sun, for that is impossible, but rather, he accepted their testimony in what they said that they saw the moon in the west in the evening, because he knew the manner of the calculations that it was possible that it would appear that same night. And concerning that which they said that it (i.e., the moon) appeared in the east in the morning, he said, that they are in error and that clouds in the form of the moon appeared to them in the firmament, and that is what is taught in the Baraitha (Tractate Rosh Hashanah 25a): One time, the sky became covered with clouds and the image of the money appeared on the twenty-[ninth] of the month, etc. Rabbi Yohanan ben Nuri said that they were false witnesses, for it appeared to him, according to his calculations, that it was not possible that moon should appear on that night that the witnesses said that they saw it, and he said that they are false witnesses because there was no time between the appearance and the beginning of the first quarter of the moon (i.e., New Moon) according to his opinion, so much time that it would be possible that it should appear on it. And on this, Rabban Gamaliel responded in the Baraitha: So I have received from the house of my father’s father, that sometimes it comes at lengthy [period of time] and sometimes it comes in a short [time], that is to say, that the time that there is between the beginning of the first quarter of the moon until the moon appears is not always equal. But there are times when the movement of the moon is quick and times when it is late. And according to the speed of the movement of the moon at that time, Rabban Gamaliel judged that it was appropriate that the moon should appear on that night, and therefore, he accepted their testimony.

ראינוהו בזמנו – on the night of the thirtieth

ובליל עבורו – on the light of the thirty-first.

וקבלן ר"ג – not because it is stated that the moon removed itself from the sun on the night of the thirtieth [of the month] until it would appear, and on the night of the thirty-first, it returned to being behind it and drew closer to the sun until it was covered, for the moon does not return to being behind it, but makes its path as it goes around in its circuit, but that Rabban Gamaliel knew in the calculations for that particular night so that when the witnesses said that they saw it, the moon had already distanced itself from the sun until it was it was possible that it would be seen. Therefore, he accepted their testimony, and regarding what they said on the night of its intercalation (i.e., proclamation of a full month) do not appear [to be valid]. It is possible that it was because the cloud covered it or another reason that caused that they (i.e., the witnesses) did not see it.

רואה אני את דבריך – to intercalate the month