And also of the son of the bond-woman will I make a nation. Literally, to nation I will set or put him; a promise already given (Genesis 17:20), but here repeated to render Ishmael's dismissal easier.
Because he is thy seed. "Thy son according to the flesh, though not after the promise, as Isaac was" (Ainsworth); a proof that men may sometimes receive mercies for their fathers' sakes.