John Chrysostom

"Notwithstanding the Lord stood with me, and strengthened me." Though deserted by man, God doth not permit him to suffer any harm. He strengthened me, he says, that is, He gave me boldness in speaking. He suffered me not to sink. "That by me the preaching might be fully known." That is, might be fulfilled. Observe his great humility. …

Homily on 2 Timothy 10 ↗

Theophylact of Ohrid

This is again a consolation for the disciple; for it shows that God does not allow a man who has been abandoned by people to suffer anything calamitous. That is, He granted boldness, He did not allow him to fall. Look how great his humility is. Not because, he says, God strengthened me so that I would be worthy of such a gift, but "that through me the preaching might be fully known," or that it might pass from end to end and be fulfilled. This is like someone wearing purple robes and a diadem, and being saved because of them. …

Commentary on 2 Timothy ↗

Thomas Aquinas

Then when he says, "but the Lord stood by me," he shows what was done against him on God's part: first, he mentions his help; second, its effect, at "that all the gentiles may hear." He says, therefore: they have all forsaken me. But where men depart, God offers himself: "for my father and my mother have left me" (Ps 26:10); hence he says, "but the Lord stood by me," namely, to help me: "but the Lord is with me as a strong warrior" (Jer 20:11); "he is at my right hand, that it be not moved" (Ps 15:8). And how? …

Commentary on 2 Timothy ↗