Genesis 15:8-11

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.