From when may we recite the Shema in the evening? From the time that the Kohanim enter to eat their terumah. [And We may recite it]. Until the end of the first watch. [These are] the words of R’ Eliezer. But the Sages say: Until midnight. Rabban Gamliel says: Until the light of dawn rises. It happened that his sons came [home] from a banquet. They said to him: We have not [yet] recited the Shema. He said to them: If the light of dawn has not yet risen, you are obligated to recite. And not only this, but all things about which the Sages said ‘‘Until midnight,’’ [the time for fulfilling] the commandment extends until the light of dawn ris-es. [For] the burning of [the sacrificial] fats and limbs [on the Altar, the time for fulfilling] the commandment extends until the light of dawn rises; and [for] all [the sacrificial parts] that are eaten for one day, [the time for fulfilling] the commandment extends until the light of dawn rises. If so, why did the Sages say: ‘‘Until midnight’’? In order to distance a person from transgression.

From when do we recite the Shema in the morning? From when one can distinguish between techeiles and white. R’ Eliezer says: between techeiles and leek. And one must finish it by sunrise. R’ Yehoshua says: By three hours, for such is the way of princes, to rise by three hours. One who recites from then and onward does not lose; [he is] like a person reading from the Torah.