Genesis 21:9-13

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!”

21:11 Sarah’s demand displeased Abraham greatly because Ishmael was his son. 21:12 But God said to Abraham, “Do not be upset about the boy or your slave wife. Do all that Sarah is telling you because through Isaac your descendants will be counted. 21:13 But I will also make the son of the slave wife into a great nation, for he is your descendant too.”