Genesis 15:13-16
15:13 Then the Lord said to Abram, “Know for certain that your descendants will be strangers in a foreign country. They will be enslaved and oppressed for four hundred years.
15:14 But I will execute judgment on the nation that they will serve. Afterward they will come out with many possessions.
15:15 But as for you, you will go to your ancestors in peace and be buried at a good old age.
15:16 In the fourth generation your descendants will return here, for the sin of the Amorites has not yet reached its limit.”