Genesis 22:10-13

Then Abraham reached out and took the knife to slaughter his son. But the angel of the LORD called to him from heaven, “Abraham, Abraham!” “Here I am,” he answered. “Do not lay your hand on the boy,” said the angel. “Do not do the least thing to him. For now I know that you fear God, since you did not withhold from me your son, your only one.” Abraham looked up and saw a single ram caught by its horns in the thicket. So Abraham went and took the ram and offered it up as a burnt offering in place of his son.