'Only Son' in the Bible

And he said, Take now your son, your only son Isaac, whom you love, and get you into the land of Moriah; and offer him there for a burnt offering upon one of the mountains which I will tell you of.

And he said, Lay not your hand upon the lad, neither do you anything unto him: for now I know that you fear God, seeing you have not withheld your son, your only son from me.

And said, By myself have I sworn, says the LORD, for because you have done this thing, and have not withheld your son, your only son: