Genesis 15:9-13

9And he said to him, Take me a heifer of three years old, and a she-goat of three years old, and a ram of three years old, and a turtle-dove, and a young pigeon.

10And he took all these, and divided them in the midst, and laid the half of each opposite its fellow; but the birds he did not divide.

11And the birds of prey came down on the carcases; and Abram scared them away.

12And as the sun was just going down, a deep sleep fell upon Abram; and behold, a horror, a great darkness, fell upon him.

13And he said to Abram, Know assuredly that thy seed will be a sojourner in a land [that is] not theirs, and they shall serve them; and they shall afflict them four hundred years.