Albert Barnes Commentary 2 Corinthians 13:2

"I have said beforehand, and I do say beforehand, as when I was present the second time, so now, being absent, to them that have sinned heretofore, and to all the rest, that, if I come again, I will not spare;" — 2 Corinthians 13:2 (ASV)

I told you before. That I would not spare offenders; that I would certainly punish them. He had indicated this before in the first epistle, 1 Corinthians 4:21; 1 Corinthians 5.

And foretell you. I now inform you of my fixed determination to punish every offender as he deserves.

As if I were present, the second time. The mention of the "second time" here proves that Paul had been with them only once before. He had formed the resolution to go to them, but had been disappointed. The time when he had been with them is recorded in Acts 18:1 and following. He now uses the same language to them that he says he would use if he were with them, as he had expected to be, the second time. See the remarks of Paley on this passage, referred to above.

And being absent. See Barnes on 1 Corinthians 5:3.

To them which heretofore have sinned. To all the offenders in the church. They had supposed that he would not come to them, 1 Corinthians 4:18, or that if he came he would not dare to inflict punishment, 2 Corinthians 10:9–11. They had, therefore, given themselves greater liberty, and had pursued their own course, regardless of his authority and commands.

I will not spare. I will punish them. They shall not escape.