Genesis 21:9-13

9But Sarah saw that the son whom Hagar the Egyptian had borne to Abraham was mocking, 10and she said to Abraham, “Get rid of that slave woman and her son, for that woman’s son will never share in the inheritance with my son Isaac.” 11The matter distressed Abraham greatly because it concerned his son. 12But God said to him, “Do not be so distressed about the boy and your slave woman. Listen to whatever Sarah tells you, because it is through Isaac that your offspring will be reckoned. 13I will make the son of the slave into a nation also, because he is your offspring.”