Galatians 4:28-31

28Now you, brothers and sisters, like Isaac, are children of promise. 29At that time the son born according to the flesh persecuted the son born by the power of the Spirit. It is the same now. 30But what does Scripture say? “Get rid of the slave woman and her son, for the slave woman’s son will never share in the inheritance with the free woman’s son.” 31Therefore, brothers and sisters, we are not children of the slave woman, but of the free woman.