Genesis 15:15-18

(As for you, you will die in peace and be buried at a ripe old age.) After four generations your descendants will return here to this land, for the sins of the Amorites do not yet warrant their destruction.” After the sun went down and darkness fell, Abram saw a smoking firepot and a flaming torch pass between the halves of the carcasses. So the LORD made a covenant with Abram that day and said, “I have given this land to your descendants, all the way from the border of Egypt to the great Euphrates River