Genesis 15:8-17

He said, “O Lord GOD, how may I know that I will possess it?” So He said to him, “Bring Me a three year old heifer, and a three year old female goat, and a three year old ram, and a turtledove, and a young pigeon.” Then he brought all these to Him and cut them in two, and laid each half opposite the other; but he did not cut the birds. The birds of prey came down upon the carcasses, and Abram drove them away. 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.” It came about when the sun had set, that it was very dark, and behold, there appeared a smoking oven and a flaming torch which passed between these pieces.