'Only Son' in the Bible

God said, "Take your son -- your only son, whom you love, Isaac -- and go to the land of Moriah! Offer him up there as a burnt offering on one of the mountains which I will indicate to you."

"Do not harm the boy!" the angel said. "Do not do anything to him, for now I know that you fear God because you did not withhold your son, your only son, from me."

and said, "'I solemnly swear by my own name,' decrees the Lord, 'that because you have done this and have not withheld your son, your only son,