Genesis 22:11-13

And behold, an angel of the Lord from heaven called to him, saying: Abraham, Abraham. And he answered: Here I am.

And he said to him: Lay not thy hand upon the boy, neither do thou any thing to him: now I know that thou fearest God, and hast not spared thy only begotten son for my sake.

Abraham lifted up his eyes, and saw behind his back a ram, amongst the briers, sticking fast by the horns, which he took and offered for a holocaust instead of his son.