John Chrysostom

"But as God is faithful, our word toward you was not yea and nay." He skillfully overturns a rising objection. For one might say, If after having promised, thou hast put off coming, and yea is not yea, and nay nay, with thee, but what thou sayest now thou unsayest afterwards, as thou didst in the case of this Journey: woe is unto us, if all this were the case in the Preaching too. …

Homily 3 on 2 Corinthians ↗

Theophylact of Ohrid

He refutes an objection that arises. Someone could quite rightly say: if what you say is unreliable, and you often say "yes" but it turns out to be "no," then we fear that your teaching and your preaching may be the same — "yes" and "no," that is, inconstant and unreliable. In refutation of this objection, he says that the promise to come to them was his own affair, and therefore it was not fulfilled; but as for the preaching, it is the work of God, and what is from God is inaccessible to falsehood. …

Commentary on 2 Corinthians ↗

Thomas Aquinas

Having enlarged upon their accusation, he excuses himself, saying, As surely as God is faithful, our word to you has not been Yes and No. In regard to this he does two things: first, he declares that he did not lie; secondly, he shows how he did not lie (v. 21). He shows in two ways that he had not lied, namely, from his character and from the cause for his not lying. From his character, because we should not suppose that a person would easily lie, if he has never been found to be a liar. …

Commentary on 2 Corinthians ↗