Genesis 15:12-16

As the sun was going down, a deep sleep fell upon Abram, and a deep and terrifying darkness descended upon him. Then the Lord said to Abram, ‘Know this for certain, that your offspring shall be aliens in a land that is not theirs, and shall be slaves there, and they shall be oppressed for four hundred years; but I will bring judgement on the nation that they serve, and afterwards they shall come out with great possessions. As for yourself, you shall go to your ancestors in peace; you shall be buried in a good old age. And they shall come back here in the fourth generation; for the iniquity of the Amorites is not yet complete.’