Mishnah Berakhot 4

¹The morning Tefillah (Shacharit) is until midday. Rabbi Judah says until the fourth hour. The afternoon Tefillah (Minhah) until evening. Rabbi Judah says: until the middle of the afternoon. The evening prayer has no fixed time. The time for the additional prayers (musaf) is the whole day. Rabbi Judah says: until the seventh hour. ²Rabbi Nehunia ben Hakaneh used to pray as he entered the Bet Hamidrash and as he left it a short prayer. They said to him: what is the reason for this prayer? He replied: When I enter I pray that that no mishap should occur through me, and when I leave I express thanks for my portion. ³Rabban Gamaliel says: every day a man should pray the eighteen [blessings]. Rabbi Joshua says: an abstract of the eighteen. Rabbi Akiva says: if he knows it fluently he prays the eighteen, and if not an abstract of the eighteen. ⁴Rabbi Eliezer says: if a man makes his prayers fixed, it is not [true] supplication. Rabbi Joshua says: if one is traveling in a dangerous place, he says a short prayer, saying: Save, O Lord, Your people the remnant of Israel. In every time of crisis may their needs be before You. Blessed are You, O Lord, who hears prayer. ⁵If he is riding on a donkey, he gets down [and prays.] If he is unable to get down he should turn his face [towards Jerusalem], and if he cannot turn his face, he should direct his heart to the Holy of Holies. ⁶If he is traveling in a ship, on a wagon or on a raft, he should direct his heart toward the Holy of Holies. ⁷Rabbi Elazar ben Azaryah says: The musaf prayer is said only with the local congregation. The sages say: whether with or with out the congregation. Rabbi Judah said in his name: wherever there is a congregation, an individual is exempt from saying the musaf prayer.