Genesis 21:6-10

And Sarah said, “God has made me laugh, and all who hear will laugh with me.” She also said, “Who would have said to Abraham that Sarah would nurse children? For I have borne him a son in his old age.” So the child grew and was weaned. And Abraham made a great feast on the same day that Isaac was weaned. And Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, scoffing. Therefore she said to Abraham, “Cast out this bondwoman and her son; for the son of this bondwoman shall not be heir with my son, namely with Isaac.”