Genesis 15:13-16

13Then the LORD said to Abram, “Know for certain that your descendants will be strangers in a land that is not their own, and they will be enslaved and mistreated four hundred years. 14But I will judge the nation they serve as slaves, and afterward they will depart with many possessions.1 15You, however, will go to your fathers in peace and be buried at a ripe old age. 16In the fourth generation your descendants will return here, for the iniquity of the Amorites is not yet complete.”