John Chrysostom

"And shall not the uncircumcision which is by nature judge?" You see, he recognizes two uncircumcisions, one from nature, and the other from the will. Here, however, he speaks of that from nature, but does not pause here, but goes on, "if it fulfil the Law, judge thee, who by the letter and circumcision dost transgress the Law?" See his exquisite judgment. …

Homily on Romans 6 ↗

Theophylact of Ohrid

Here he clearly shows that he means two uncircumcisions, one natural and the other voluntary, which occurs, as was said, when someone in no way cuts off the carnal passions, and two circumcisions, one according to the flesh and the other a circumcision of the heart in the spirit. …

Commentary on Romans ↗

Irenaeus

And that the Lord did not abrogate the natural [precepts] of the law, by which man is justified, which also those who were justified by faith, and who pleased God, did observe previous to the giving of the law, but that He extended and fulfilled them, is shown from His words. "For," He remarks, "it has been said to them of old time, Do not commit adultery. …

Irenaeus Against Heresies Book 4 ↗

Thomas Aquinas

Second, at and will not that which by nature, he shows that on account of observing the law the gentile is preferred to the Jew. Hence he says, will not that which by nature is uncircumcision, i.e., an uncircumcised gentile, if it fulfill the law through natural reason, judge you, the circumcised Jew, who by the letter is a transgressor of the law, by transgressing the precepts of the law, and have circumcision, i.e., of the flesh. …

Commentary on Romans ↗