Heb 11:17-19
17 By faith, Abraham, at the time of testing, offered Isaac back to God. Acting in faith, he was as ready to return the promised son, his only son, as he had been to receive him — 18 and this after he had already been told, "Your descendants shall come from Isaac." 19 Abraham figured that if God wanted to, he could raise the dead. In a sense, that's what happened when he received Isaac back, alive from off the altar.