Genesis 21:11-13

And the thing was very grievous in Abraham's sight because of his son.

And God said unto Abraham, Let it not be grievous in thy sight because of the lad, and because of thy bondwoman; in all that Sarah hath said unto thee, hearken unto her voice; for in Isaac shall thy seed be called.

And also of the son of the bondwoman will I make a nation, because he is thy seed.