Genesis 15:8-11

But Abram replied, “O Sovereign LORD, how can I be sure that I will actually possess it?” The LORD told him, “Bring me a three-year-old heifer, a three-year-old female goat, a three-year-old ram, a turtledove, and a young pigeon.” So Abram presented all these to him and killed them. Then he cut each animal down the middle and laid the halves side by side; he did not, however, cut the birds in half. Some vultures swooped down to eat the carcasses, but Abram chased them away.