For the promise to Abraham and his offspring that he would be heir of the world was not given through the law, but through the righteousness that comes by faith.
13. For the promise, etc. He now more clearly sets the law and faith in opposition, the one to the other, which he had before in some measure done; and this ought to be carefully observed: for if faith borrows nothing from the law in order to justify, we hence understand, that it has respect to nothing else but to the mercy of God.
Abraham received justification by faith fourteen or twenty-five years before circumcision, silencing the fears of the uncircumcised Gentiles and humbling the pride of the Jews who boasted in their circumcision as if it held a monopoly on blessing. Circumcision came only afterward as a seal and confirmation of righteousness already imputed.
AI summary
Commenting on Romans 4:9-16
For if they which are of the law be heirs,.... That is, if the Jews who are under the law, and are seeking for righteousness and life by the works of it, should, on the account of their obedience to it, be heirs of the grace of life and of glory, faith is made void; for if the right to the inheritance is by the...