Paul is praying that he and his colleagues will be humbled, as it were, by seeing the Corinthians so well behaved that he will not dare rebuke them. If they are humbled in this way, they will appear to be false. It is when they judge sinners with the authority granted to them that they are seen to be approved as genuine by God. If then there are no people for them to judge, it looks as if they have been proved false through the lessening of their authority.
Then when he has held the threat suspended over their heads, and brought the punishment now up to their doors, and has set them a trembling, and made them look for vengeance; see how again he sweetens down his words and soothes their fear, and shows his unambitious temper, his tender solicitude towards his disciples, his high-principledness of purpose, his loftiness and freedom from vain-glory.
What can be equal to this soul? He was despised, he was spit upon, he was ridiculed, he was mocked, as mean, as contemptible, as a braggart, as boastful in his words but in his deeds unable to make even a little show; and although seeing so great a necessity for showing his own power, he not only puts off, not only shrinks back, but even prays that he may not fall into such a position. For he says, "I pray that ye do no evil, not that we may appear approved, but that ye may do that which is honorable, though we be as reprobate."
What is it he says? "I entreat God. I beseech Him," he says, "that I may find no one unreformed, may find no one that has not repented; yea, rather, not this alone, but that none may have sinned at all. For," he says, "that ye have done no [evil], but if ye have perchance sinned, then that ye may have changed your conduct, and been beforehand with me in reforming, and arresting all wrath. For this is not what I am eager about, that we should be approved in this way, but clean the contrary, that we should not appear approved. For if ye should continue," he says, "sinning and not repenting, it will be necessary for us to chastise, to punish, to maim your bodies; (as happened in the case of Sapphira and of Magus;) and we have given proof of our power. But we pray not for this, but the contrary, that we may not be shown to be approved in this way, that we may not in this way exhibit the proof of the power which is in us, by chastising you and punishing you as sinning and as incurably diseased."
But what? "That ye should do that which is honorable," we pray for this, that ye should ever live in virtue, ever in amendment; "and we should be as reprobate," not displaying our power of punishing. And he said not, "reprobate" for he would not "be" reprobate, even though he did not punish, nay rather for this very reason he would be "approved;" "but even if some suspect us," he says, "on account of our not displaying our power, to be contemptible and cast away, we care nothing for this. Better we should be so deemed of by those, than display the power which God hath given to us in those stripes, and in that unreformedness of heart."
[AD 384] Ambrosiaster on 2 Corinthians 13:7