Therefore fear not, Jacob, my servant (Jeremiah: 30:10)

This speaks of Jacob, of whom it is written and he dreamed, and behold, a ladder set up on the earth... and behold the angels of God ascending and descending on it. Rabbi Berekiah and Rabbi Helbo and Rabbi Shimon bar Yohai in the name of Rabbi Meir said: It teaches that the Holy One, the blessed One, showed Jacob the Prince of Babylon... of Media... of Greece... and of Edom ascending and descending. Then God said to Jacob: "You also ascend." Our father Jacob was afraid, and thought: Perhaps, heaven forbid, in the same way as these nations descended, I will also have to descend. Said the Holy One, the blessed One: Fear not, Jacob my servant. Once you ascend there will be no descent for you. Jacob would not believe and did not ascend.
Leviticus Rabbah 29:2; Pesikta De-Rab Kahana 23:2)