Genesis 21:8-10

21:8 The child grew and was weaned. Abraham prepared a great feast on the day that Isaac was weaned. 21:9 But Sarah noticed the son of Hagar the Egyptian – the son whom Hagar had borne to Abraham – mocking. 21:10 So she said to Abraham, “Banish that slave woman and her son, for the son of that slave woman will not be an heir along with my son Isaac!”