Abraham's Dread and Great Darkness as the Four Exiles

"And when the sun was going down, a deep sleep [tardemah] fell upon Abram" (Genesis 15:12). Rabbi Yehoshua of Sikhnin in the name of Rabbi Levi: The beginning of a downfall is sleep; he lies down and does not labor in Torah, he lies down and does not labor in work. Rav said: There are three kinds of deep sleep. The deep sleep of slumber, "And the LORD God caused a deep sleep to fall upon the man, and he slept" (Genesis 2:21). The deep sleep of prophecy, "And a deep sleep fell upon Abram." The deep sleep of stupor, as it is said, "And no one saw and no one knew and no one awoke, for they were all asleep, because a deep sleep from the LORD had fallen upon them" (1 Samuel 26:12). And the Rabbis say: Also a deep sleep of folly, as it is said, "For the LORD has poured over you a spirit of deep sleep" (Isaiah 29:10). Rabbi Chanina son of Rabbi Yitzchak said: There are three faded fruits [unripe forerunners]. The faded fruit of death is sleep; the faded fruit of prophecy is a dream; the faded fruit of the world to come is the Sabbath. Rabbi Avin adds two more: the faded fruit of the light above is the disk of the sun; the faded fruit of the wisdom above is the Torah. "And behold, a dread" (Genesis 15:12), this is Babylon, as it is written, "Then Nebuchadnezzar was filled with fury" (Daniel 3:19). "Darkness," this is Media, which darkened the eyes of Israel with fasting and affliction. "Great," this is Greece. Rabbi Simon said: it raised up a hundred and twenty dukes, a hundred and twenty governors, a hundred and twenty commanders. And the Rabbis say: it raised them sixty by sixty, as it is written, "serpent, fiery serpent, and scorpion" (Deuteronomy 8:15); just as a scorpion bears young sixty at a time, so the kingdom of Greece raised them sixty by sixty. "Fell upon him," this is the fourth kingdom, as it is written, "At the sound of their fall the earth trembled" (Jeremiah 49:21). And some reverse it: "falling" is Babylon, "fallen, fallen is Babylon" (Isaiah 21:9); "great" is Media, "the king Ahasuerus made great" (Esther 3:1); "darkness" is Greece, which darkened the eyes of Israel with decrees, for they would say, "Write on the horn of an ox that you have no portion in the God of Israel"; "dread" is the fourth kingdom, "dreadful and terrible and exceedingly strong" (Daniel 7:7). "And He said to Abram, Know surely" (Genesis 15:13): know that I will scatter them, and be sure that I will gather them; know that I will enslave them, and be sure that I will redeem them. "That your seed shall be a stranger": from the time that seed shows itself to you, four hundred years. Rabbi Yudan said: the strangerhood, the slavery, and the affliction in a land not theirs, four hundred years to their term.