Romans 4:11-13, 16

It was later that he received the external sign of circumcision as a seal to confirm that God had already transferred his righteousness to him by faith, while he was still uncircumcised. So now this qualifies him to become the father of all who believe among the non-Jewish people. And like their “father of faith,” Abraham, God also transfers his righteousness to them by faith. Yes, Abraham is obviously the true father of faith for the Jewish people who are not only circumcised but who walk in the way of faith that our father Abraham displayed before his circumcision. God promised Abraham and his descendants that they would have an heir who would reign over the world. This royal promise was not fulfilled because Abraham kept all the law, but through the righteousness that was transferred by faith.

The promise depends on faith so that it can be experienced as a grace-gift, and now it extends to all the descendants of Abraham. This promise is not only meant for those who obey the law, but also to those who enter into the faith of Abraham, the father of us all.