Genesis 15:8-12, 17-18

And he said, Lord GOD, whereby shall I know that I shall inherit it? And he said unto him, Take me an heifer of three years old, and a she goat of three years old, and a ram of three years old, and a turtledove, and a young pigeon. And he took unto him all these, and divided them in the midst, and laid each piece one against another: but the birds divided he not. And when the fowls came down upon the carcases, Abram drove them away. And when the sun was going down, a deep sleep fell upon Abram; and, lo, an horror of great darkness fell upon him.

And it came to pass, that, when the sun went down, and it was dark, behold a smoking furnace, and a burning lamp that passed between those pieces. In the same day the LORD 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