“ It once happened that [Rabban Gamliel’s] sons came [home late at night] from a place of feasting. They said to [their father] : “We have not recited the Shema." He said to them: “If dawn has not broken, you are obligated to recite it. ”

“ Burning the fats and organs [of the sacrifices, on the Temple altar] — this precept [can be performed] until the break of dawn. [Another example:] All [sacrifices] which may be eaten for one day — the precept [of eating them can be performed] until the break of dawn.
"If so, why did the Sages say [that these precepts can be performed only] until midnight? To keep a person away from sinning."
Gemara What does the Tanna refer to, asking "Since when"? Furthermore, why does he deal with [the Shema reading] of the evening first, rather than dealing with that of the morning first? ”