Genesis 15:10

⁸  And he said, LORD God, whereby shall I know that I shall inherit it?

⁹  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.

¹⁰  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.

¹¹  And when the fowls came down upon the carcasses, Abram drove them away.

¹²  And when the sun was going down, a deep sleep fell upon Abram; and, lo, an horror of great darkness fell upon him.