Genesis 21:8-13 (New International Version)

Hagar and Ishmael Sent Away

 ⁸ The child grew and was weaned, and on the day Isaac was weaned Abraham held a great feast. ⁹ But Sarah saw that the son whom Hagar the Egyptian had borne to Abraham was mocking, ¹⁰ and she said to Abraham, "Get rid of that slave woman and her son, for that slave woman's son will never share in the inheritance with my son Isaac."

 ¹¹ The matter distressed Abraham greatly because it concerned his son. ¹² But God said to him, "Do not be so distressed about the boy and your maidservant. Listen to whatever Sarah tells you, because it is through Isaac that your offspring ^[a] will be reckoned. ¹³ I will make the son of the maidservant into a nation also, because he is your offspring."