Génesis 7:5 Midrash: Ein Yaakov (Glick Edition) & Bereshit Rabbah

(Fol. 8) Our Rabbis were taught: When Adam the first man saw that each week the day became shortened, he started to cry, saying: "Woe is to me, perhaps this is because of my sin that the world becomes dark to me, and it might yet return to chaos and ruin. And this must be the [punishment of] death which was decreed upon me by Heaven." He sat fasting and praying for eight days. Thereafter, when he lived to see the solstice of the month of Tebeth, beholding that the days become longer, he understood that such is the cycle of the world. He thereupon established eight holidays. On the next year, he added the eight days in which he had fasted, as holidays. But while he established them to laud heaven, his descendants, however, made them holidays for the idols. Our Rabbis were taught: When Adam, the first man, saw on the first day of his creation, the sun set, he cried, saying: "Woe is to me, perhaps this is because of my sin that the world is to be returned to chaos. And this must be the [punishment of] death which was decreed upon me by Heaven." He wept all night, and Eve did the same opposite him. However, when dawn appeared, he understood that such was the order of the world. He arose and sacrificed an ox, whose horns preceded its hoofs (was born full-grown) as it is said (Ps. 69, 32) And it shall please the Lord better than a bullock that has horns and hoofs. (Fol. 9) At the college of Elijah it was taught: The world will continue for six thousand years, the first two thousand of which were a chaos (Tohu, without the Torah), the second two thousand were of Torah, and the third two thousand are the days of the Messiah, and because of our sins many years of these have elapsed [and still he has not come]. Let us see from what time are the two thousand of Torah counted? Shall we assume it to be the time when the Torah was given to Israel? Two thousand years have not elapsed as yet; for if you will go over carefully the years of Tohu, you will find that they were more than two thousand. We must therefore say [that it begins] from the time metioned: (Gen. 7, 5) And the persons that they had obtained in Charan. And it is known by tradition that Abraham was then fifty-two years of age. And from his fifty-second year until the Torah was given, four hundred and forty-eight years elapsed, and these years will complete the number of two thousand which were lacking at the time when the Tanna taught concerning the two thousand years of wisdom.

“For in seven more days, I will make it rain upon the earth forty days and forty nights, and I will obliterate all existence that I made from on the face of the earth” (Genesis 7:4).
“For in seven more days, [I will make it rain upon the earth forty days and forty nights]” – Rabbi Shimon ben Yoḥai said: They violated the Torah that was given in forty days; therefore, [the Flood lasted] “forty days and forty nights.” Rabbi Yoḥanan ben Zakai said: They corrupted the human form that comes into being at forty days,¹⁶A fetus is considered to possess human form after forty days of gestation. therefore [the Flood lasted] “forty days and forty nights.”
“I will obliterate all existence [hayekum]” – Rabbi Berekhya said: The living beings [kiyum]. Rabbi Avun said : Its sustainers [yekuminei].¹⁷Mankind. Rabbi Levi said in the name of Reish Lakish: This refers to Cain,¹⁸Who “rose up” [kam] against Abel to kill him (Genesis 4:8). who had been suspended in abeyance until the Flood came and swept him away, as it is stated: “He obliterated all existence [yekum]” (Genesis 7:23).
“Noah did; according to everything that God commanded him, so he did” (Genesis 6:22) – this pertains to the gathering of the animals, beasts, and birds.