John Chrysostom, on Rom 3:31

"Do we then," he says, "make void the Law through faith? God forbid: yea, we establish the Law." Do you see his varied and unspeakable judgment? For the bare use of the word "establish" shows that it was not then standing, but was worn out. And note also Paul's exceeding power, and how superabundantly he maintains what he wishes. For here he shows that the faith, so far from doing any disparagement to the "Law," even assists it, as it on the other hand paved the way for the faith. For as the Law itself before bore witness to it (for he saith, "being witnessed by the Law and the Prophets"), so here this establisheth that, now that it is unnerved. And how did it establish? he would say. What was the object of the Law and what the scope of all its enactments? Why, to make man righteous. But this it had no power to do. "For all," it says, "have sinned:" but faith when it came accomplished it. For when a man is once a believer, he is straightway justified. The intention then of the Law it did establish, and what all its enactments aim after, this hath it brought to a consummation. Consequently it has not disannulled, but perfected it. Here then three points he has demonstrated; first, that without the Law it is possible to be justified; next, that this the Law could not effect; and, that faith is not opposed to the Law.