Tractate Rosh Hashanah - Chapter 2 - Mishnah 9 ראש השנה פרק ב׳ משנה ט׳

Rabban Gamaliel sent to him: I order you to appear before me with your staff and your money on the day which according to your count should be Yom Hakippurim. Rabbi Akiva went and found him in distress. He said to him: I can teach that whatever Rabban Gamaliel has done is valid, because it says, “These are the appointed seasons of the Lord, holy convocations, which you shall proclaim at their appointed times” (Leviticus 23:4), whether they are [proclaimed] at their proper time or not at their proper time, I have no other appointed times save these. He [Rabbi Joshua] then went to Rabbi Dosa ben Harkinas. He said to him: if we call in question the court of Rabban Gamaliel we must call in question the decisions of every court which has existed since the days of Moses until now. As it says, “Then Moses and Aaron, Nadav and Avihu and seventy of the elders of Israel went up” (Exodus 24:9). Why were the names of the elders not mentioned? To teach that every group of three which has acted as a court over Israel, behold it is like the court of Moses. He [Rabbi Joshua] took his staff and his money and went to Yavneh to Rabban Gamaliel on the day which according to his count should be Yom Hakippurim. Rabban Gamaliel rose and kissed him on his head and said to him: Come in peace, my teacher and my student my teacher in wisdom and my student because you have accepted my decision.