John Chrysostom

"For I will not dare to speak of any of those things which Christ hath not wrought by me, to make Gentiles obedient by word and deed, through mighty signs and wonders, by the power of the Spirit of God." And none, he means, can say that my words are a mere boast. For of this priestly ministry of mine, the signs that I have, and the proofs of the appointment too, are many. Not the long garment and the bells as they of old, nor the mitre and the turban, but signs and wonders, far more awful than these. …

Homily on Romans 29 ↗

Theophylact of Ohrid

Since he said of himself: I am a minister of the Gospel to all nations, he adds: I do not boast or pride myself on anything that I have not done; indeed, I did not do it, but Christ did, using me as an instrument. Whether I speak something, discoursing and philosophizing about heavenly things, or whether I do something, leading a life according to God, or whether I perform miracles—all this belongs to Christ.

Commentary on Romans ↗

Thomas Aquinas

Then he assigns the reason for what he had said, saying: for I dare not speak of any of those things which Christ does not work by me. As if to say: I will not speak about the fruit produced through me, because it was not produced by me. Otherwise, I would have no glory with God, even if with men. What I do relate are things not as accomplished chiefly through me, but as done by Christ though me: O Lord, you have wrought for us all our works (Isa 27:12). Second, he mentions the fruit itself, saying: for the obedience of the gentiles. …

Commentary on Romans ↗