Genesis 21:9-12

But Sarah saw Ishmael—the son of Abraham and her Egyptian servant Hagar—making fun of her son, Isaac. So she turned to Abraham and demanded, “Get rid of that slave woman and her son. He is not going to share the inheritance with my son, Isaac. I won’t have it!” This upset Abraham very much because Ishmael was his son. But God told Abraham, “Do not be upset over the boy and your servant. Do whatever Sarah tells you, for Isaac is the son through whom your descendants will be counted.