Genesis 21:9

⁷  And she said, Who would have said unto Abraham, that Sarah should have given children suck? for I have born him a son in his old age.

⁸  And the child grew, and was weaned: and Abraham made a great feast the same day that Isaac was weaned.

⁹  And Sarah saw the son of Hagar the Egyptian, which she had born unto Abraham, mocking.

¹⁰  Wherefore she said unto Abraham, Cast out this bondwoman and her son: for the son of this bondwoman shall not be heir with my son, even with Isaac.

¹¹  And the thing was very grievous in Abraham's sight because of his son.