Genesis 15:12-16

Now when the sun was going down, a deep sleep fell upon Abram; and behold, terror and great darkness fell upon him. God said to Abram, “Know for certain that your descendants will be strangers in a land that is not theirs, where they will be enslaved and oppressed four hundred years. But I will also judge the nation whom they will serve, and afterward they will come out with many possessions. As for you, you shall go 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 Amorite is not yet complete.”