Genesis 22:10-13

He then took the knife and got ready to kill his son. But the LORD's angel shouted from heaven, “Abraham! Abraham!” “Here I am!” he answered. “Don't hurt the boy or harm him in any way!” the angel said. “Now I know that you truly obey God, because you were willing to offer him your only son.” Abraham looked up and saw a ram caught by its horns in the bushes. So he took the ram and sacrificed it in place of his son.