Beis Shammai say: In the evening all people must lie down and recite [the Shema], and in the morning they must stand, for it is stated: When you lie down and when you arise (Deuteronomy 6:7). But Beis Hillel say: Every person recites according to his [preferred] manner, for it is stated (ibid.): While you walk on the way. If so, why is it stated: When you lie down and when you arise (Deuter-onomy 11:19)? At the time when people go to sleep and at the time when people get up. R’ Tarfon said: I was coming on the road, and I lay down to recite in accordance with the words of Beis Shammai, and I endangered myself on account of the bandits. They said to him: It would have been fitting for you to come to harm, for you trans-gressed the words of Beis Hillel.

In the morning one recites two blessings before [the Shema] and one after it, and in the evening [one recites] two [blessings] before [the Shema] and two after it; one lengthy [blessing] and one brief [one]. Where they said to recite a lengthy [blessing], one may not shorten [it]; [where they said] to recite a brief [blessing], one may not lengthen [it]. [Where they said] to con-clude [a blessing] with a closing formula, one may not conclude [the blessing] without the closing formula; and [where they said] not to conclude [a blessing] with a closing formula, one may not conclude [the blessing] with a closing formula.