'Unique' in the Bible

God said, "Please take your son, your unique son whom you love Isaac and go to the land of Moriah. Offer him as a burnt offering there on one of the mountains that I will point out to you."

"Don't lay your hand on the youth!" he said. "Don't do anything to him, because I've just demonstrated that you fear God, since you have not withheld your son, your only unique one, from me."

and said, "I have taken an oath to swear by myself," declares the LORD, "that since you have carried this out and have not withheld your only unique son,