Genesis 22:8-13

   8: And Abraham said, My son, God will provide himself a lamb for a burnt offering: so they went both of them together.
   9: And they came to the place which God had told him of; and Abraham built an altar there, and laid the wood in order, and bound Isaac his son, and laid him on the altar upon the wood.
   10: And Abraham stretched forth his hand, and took the knife to slay his son.
   11: And the angel of the LORD called unto him out of heaven, and said, Abraham, Abraham: and he said, Here am I.
   12: And he said, Lay not thine hand upon the lad, neither do thou any thing unto him: for now I know that thou fearest God, seeing thou hast not withheld thy son, thine only son from me.
   13: And Abraham lifted up his eyes, and looked, and behold behind him a ram caught in a thicket by his horns: and Abraham went and took the ram, and offered him up for a burnt offering in the stead of his son.