Genesis 21:8-13

The child grew and was weaned, and Abraham made a great feast on the day that Isaac was weaned. Now Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, mocking. Therefore she said to Abraham, “Drive out this maid and her son, for the son of this maid shall not be an heir with my son Isaac.” The matter distressed Abraham greatly because of his son. But God said to Abraham, “Do not be distressed because of the lad and your maid; whatever Sarah tells you, listen to her, for through Isaac your descendants shall be named. And of the son of the maid I will make a nation also, because he is your descendant.”