John Chrysostom

So he first adopted a form of adjuration, because it was an absurd thing he had named. And then he makes his discourse pass on to exhortation, and shows the great facility of the struggle.

Homily on Romans 11 ↗

Theophylact of Ohrid

The apostle always proposes such objections, which is why he both raises and resolves them, as he does with the present objection, answering it: "God forbid." Then he proves that it is not difficult for us not to sin. Consider, he urges, in your mind which is better: to be slaves of sin, having surrendered to it of your own will (this is what "you yield" means), and to receive as a reward death, that is, eternal punishment (for the sin of Adam produced bodily and temporal death, but sin committed now subjects a person to eternal …

Commentary on Romans ↗

Clement of Alexandria

The noble apostle himself refutes the charge against him implied in their false exegesis by the words with which he continues after the saying just quoted: "What then? Shall we sin because we are not under the law but under grace? God forbid." In this inspired and prophetic way he at once destroys the device of these licentious sophists.

The Stromata Book 3 ↗

Thomas Aquinas

Then when he says, what then, he raises a question against what he has said. And concerning this he does three things: first, he raises the question; second, he answers it, at God forbid! Know you not; third, he shows how unfitting it would be to misinterpret his statement, at but thanks be to God. In regard to the first it should be noted that his statement could be falsely interpreted, namely, that Christ's faithful are not under the law with respect to being obliged to obey its moral precepts. …

Commentary on Romans ↗