Genesis 15:12-16

When the sun was about to set and a deep sleep fell on Abram, behold, terror of great darkness was falling upon him! Then He said to Abram, “Know for certain that your seed will be strangers in a land that is not theirs, and they will be enslaved and oppressed 400 years. But I am going to judge the nation that they will serve. Afterward they will go out with many possessions. But you, you will come to your fathers in peace. You will be buried at a good old age. Then in the fourth generation they will return here—for the iniquity of the Amorites is not yet complete.”