(2) Speak to the Israelite people and say to them:
These are My fixed times, the fixed times of GOD, that you shall proclaim as sacred occasions.

(8)Rabban Gamliel had a diagram of the different forms of the moon drawn on a tablet that hung on the wall of his attic, which he would show to the laymen who came to testify about the new moon but were unable to describe adequately what they had seen. And he would say to them: Did you see a form like this or like this? There was an incident in which two witnesses came to testify about the new moon, and they said: We saw the waning moon in the morning in the east,and that same day we saw the new moon in the evening in the west. Rabbi Yoḥanan ben Nuri said: They are false witnesses, as it is impossible to see the new moon so soon after the last sighting of the waning moon. However, when they arrived in Yavne, Rabban Gamliel accepted them as witnesses without concern. And there was another incident in which two witnesses came and said: We saw the new moon at its anticipated time, i.e., on the night of the thirtieth day of the previous month; however, on the following night, i.e., the start of the thirty-first, which is often the determinant of a full, thirty-day month, it was not seen. And nevertheless Rabban Gamliel accepted their testimony and established the New Moon on the thirtieth day. Rabbi Dosa ben Horkinas disagreed and said: They are false witnesses; how can witnesses testify that a woman gave birth and the next day her belly is between her teeth, i.e., she is obviously still pregnant? If the new moon was already visible at its anticipated time, how could it not be seen a day later? Rabbi Yehoshua said to him: I see the logic of your statement; the New Moon must be established a day later.

(9) Upon hearing that Rabbi Yehoshua had challenged his ruling, Rabban Gamliel sent a message to him: I decree against you that you must appear before me with your staff and with your money on the day on which Yom Kippur occurs according to your calculation; according to my calculation, that day is the eleventh of Tishrei, the day after Yom Kippur. Rabbi Akiva went and found Rabbi Yehoshua distressed that the head of the Great Sanhedrin was forcing him to desecrate the day that he maintained was Yom Kippur. In an attempt to console him, Rabbi Akiva said to Rabbi Yehoshua: I can learn from a verse that everything that Rabban Gamliel did in sanctifying the month is done, i.e., it is valid. As it is stated: “These are the appointed seasons of the Lord, sacred convocations, which you shall proclaim in their season” (Leviticus 23:4). This verse indicates that whether you have proclaimed them at their proper time or whether you have declared them not at their proper time, I have only these Festivals as established by the representatives of the Jewish people. Rabbi Yehoshua then came to Rabbi Dosa ben Horkinas, who said to him: If we come to debate and question the rulings of the court of Rabban Gamliel, we must debate and question the rulings of every court that has stood from the days of Moses until now. As it is stated: “Then Moses went up, and Aaron, Nadav and Avihu, and seventy of the Elders of Israel” (Exodus 24:9). But why were the names of these seventy Elders not specified? Rather, this comes to teach that every set of three judges that stands as a court over the Jewish people has the same status as the court of Moses. Since it is not revealed who sat on that court, apparently it is enough that they were official judges in a Jewish court. When Rabbi Yehoshua heard that even Rabbi Dosa ben Horkinas maintained that they must submit to Rabban Gamliel’s decision, he took his staff and his money in his hand, and went to Yavne to Rabban Gamliel on the day on which Yom Kippur occurred according to his own calculation. Upon seeing him, Rabban Gamliel stood up and kissed him on his head. He said to him: Come in peace, my teacher and my student. You are my teacher in wisdom, as Rabbi Yehoshua was wiser than anyone else in his generation, and you are my student, as you accepted my statement, despite your disagreement.

Rabbi Akiva said to him: My teacher, allow me to say before you one matter that you yourself once taught me. He said to him: Speak. He said to him: It states with respect to the Festivals: “The appointed seasons of the Lord, which you shall proclaim them [otam] to be sacred convocations (Leviticus 23:2). And it is written: “These are the appointed seasons of the Lord, sacred convocations; you shall proclaim them [otam] in their season” (Leviticus 23:4). And it is written: “These are the appointed seasons of the Lord; you shall proclaim them [otam] to be sacred convocations” (Leviticus 23:37). Three times the verses use the term: Them [otam], which can also be read as you [atem], in plural. This comes to teach: You [atem] are authorized to determine the date of the new month, even if you unwittingly establish the New Moon on the wrong day; you, even if you do so intentionally; you, even if you are misled by false witnesses. In all cases, once the court establishes the day as the New Moon, it is sanctified, and God grants His consent. After hearing this, Rabbi Yehoshua said to him in these words: Akiva, you have consoled me; you have consoled me.