Related do Diwrej ha-jamim II 6:38

Just like the Torah established a set time to read the Shema, so too the Sages established a set time for [the] prayer [of Shemoneh Esreh]. Why did they say [that] the morning prayer [of Shmoneh Esreh can be prayed only] until noon? Because the morning Tamid (daily offering) [sacrifice] could be brought [only] until noon. Rebbi Yehudah says, “[The morning prayer of Shmoneh Esreh can be prayed only] until [the end of the first] four hours [of the day].” And why did they say that the Mincha (afternoon) prayer [of Shemoneh Esreh can only be prayed] until the evening? Because the afternoon Tamid [sacrifice] could be brought [only] until the evening. Rebbi Yehudah says, “[The Mincha prayer of Shmoneh Esreh can be prayed only] until Plag Hamincha.” And when is Plag Hamincha? Eleven minus one quarter hours [of the day] (i.e. 10 ¾ hours). And why did they say that the evening prayer [of Shmoneh Esreh] does not have a set time? Because the limbs and fats [of the sacrifices] could be brought the whole night. And why did they say that the Mussaf prayer [of Shmoneh Esreh can be prayed] the whole day? Because the Mussaf (additional offering) sacrifice could be brought the whole day. Rebbi Yehudah says, “[The Mussaf prayer can be prayed] until [the end of the first] seven hours [of the day].”