Genesis 15:8-10

8But Abram said, “Sovereign LORD, how can I know that I will gain possession of it?”

9So the LORD said to him, “Bring me a heifer, a goat and a ram, each three years old, along with a dove and a young pigeon.” 10Abram brought all these to him, cut them in two and arranged the halves opposite each other; the birds, however, he did not cut in half.