Genesis 15:13-16

13Then the Lord said to him, “Know for certain that for four hundred years your descendants will be strangers in a country not their own and that they will be enslaved and mistreated there. 14But I will punish the nation they serve as slaves, and afterward they will come out with great possessions. 15You, however, will go to your ancestors in peace and be buried at a good old age. 16In the fourth generation your descendants will come back here, for the sin of the Amorites has not yet reached its full measure.”