Genesis 21:9-12

But Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, laughing. So she said to Abraham, “Cast out this slave woman with her son, for the son of this slave woman shall not be heir with my son Isaac.” And the thing was very displeasing to Abraham on account of his son. But God said to Abraham, “Be not displeased because of the boy and because of your slave woman. Whatever Sarah says to you, do as she tells you, for through Isaac shall your offspring be named.