Genesis 15:15-18

But thou shalt go to thy fathers in peace; thou shalt be buried in a good old age. And in the fourth generation they shall come hither again: for the iniquity of the Amorite is not yet full. And it came to pass, that, when the sun went down, and it was dark, behold, a smoking furnace, and a flaming torch that passed between these pieces. In that day Jehovah made a covenant with Abram, saying, Unto thy seed have I given this land, from the river of Egypt unto the great river, the river Euphrates