Genesis 15:15

And he said unto Abram, Know of a surety that thy seed shall be a stranger in a land that is not theirs, and shall serve them; and they shall afflict them four hundred years;

And also that nation, whom they shall serve, will I judge: and afterward shall they come out with great substance.

But in the fourth generation they shall come hither again: for the iniquity of the Amorites is not yet full.

And it came to pass, that, when the sun went down, and it was dark, behold a smoking furnace, and a burning lamp that passed between those pieces.