Genesis 15:7-12

And he said to him, “I am the LORD who brought you out from Ur of the Chaldeans to give you this land to possess.” But he said, “O Lord GOD, how am I to know that I shall possess it?” He said to him, “Bring me a heifer three years old, a female goat three years old, a ram three years old, a turtledove, and a young pigeon.” And he brought him all these, cut them in half, and laid each half over against the other. But he did not cut the birds in half. And when birds of prey came down on the carcasses, Abram drove them away. As the sun was going down, a deep sleep fell on Abram. And behold, dreadful and great darkness fell upon him.