Galatians 4:30 NIV

Genesis 21:10-12 NIV
and 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.” The matter distressed Abraham greatly because it concerned his son. But 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.