Galatians 4:28

4:28 But you, brothers and sisters, are children of the promise like Isaac.

Galatians 3:18

3:18 For if the inheritance is based on the law, it is no longer based on the promise, but God graciously gave it to Abraham through the promise.

Galatians 4:23

4:23 But one, the son by the slave woman, was born by natural descent, while the other, the son by the free woman, was born through the promise.