Pirkei Avot 1:1 and Berakhot 2a

(1) Moshe received the Torah from Sinai and transmitted it to Yehoshua, and Yehoshua to the Elders, and the Elders to the Prophets, and the Prophets transmitted it to the Men of the Great Assembly. They said three things: Be deliberate in judgment, raise up many disciples and make a fence for the Torah.

(1) From when may one recite Shema in the evening? From the time when the kohanim go in to eat their ​terumah until the end of the first watch – so says Rabbi Eliezer. And the Sages say: Until midnight. Rabban Gamliel says: Until the break of dawn. It once happened that his [Rabban Gamliel’s] sons came home late from a wedding party. They said to him: We have not recited Shema. He said to them: If dawn has not broken, you are obligated to recite it. And not only in this case; rather, in all cases where the Sages say "until midnight" — their precepts are [still in force] until the break of dawn. [For example:] Burning the fats and limbs [of the sacrifices, on the Temple altar] — their precepts [can be performed] until the break of dawn. And [another example:] all [sacrifices] which may be eaten for one day — their precepts [of eating them can be performed] until the break of dawn. If that is so, why did the Sages say, "until midnight"? To distance a person from transgression.