Berakhot 3a
And signs of the transition between each of these watches in the upper world can be sensed in this world: In the first watch, the donkey brays; in the second, dogs bark; and in the third people begin to rise, a baby nurses from its mother’s breast and a wife converses with her husband. With regard to these earthly manifestations of the three heavenly watches as established in the baraita, the Gemara asks: What did Rabbi Eliezer enumerate? If he enumerated the beginning of the watch, why do I need a sign for the beginning of the first watch? It is when evening begins; an additional sign is superfluous. If he enumerated the end of the watches, why do I need a sign for the end of the last watch? It is when day begins; an additional sign is similarly superfluous. The Gemara answers: Rather, he enumerated the signs for the end of the first watch and the beginning of the last watch, both of which require a sign, as well as the middle of the middle watch. And if you wish, say instead: He enumerated the ends of all of the watches. And if you say that a sign indicating the end of the final watch is unnecessary because it is day, nevertheless, that sign is useful.
Berakhot 34b
And Rabbi Ḥiyya bar Abba said that Rabbi Yoḥanan said: All the prophets only prophesied with regard to the change in world order in the end of days with regard to the days of the Messiah. However, with regard to the World-to-Come, which exists on a higher level, it is stated: “No eye has seen it, God, aside from You.”
Menachot 31b
The Gemara explains their dispute: The one who says that one writes it at the end of the final line interprets the verse: “That your days may be multiplied, and the days of your children, upon the land which the Lord swore unto your fathers to give them, as the days of the heaven above the earth,” in a similar manner to the verse: “For as the heaven is high above the earth” (Psalms 103:11). Consequently, if one writes “above the earth” at the end of the final line, it will appropriately be below the term “the heaven” at the end of the previous line. And the one who says that one writes it at the beginning of the final line explains the phrase “as the days of the heaven above the earth” as meaning: Just as the heaven is far from the earth. Consequently, if one writes “above the earth” at the beginning of the final line, it is far from the term “the heaven” at the end of the previous line.