Verse 1
2 Corinthians 13:1
This is the third time -- (see the note on 2 Corinthians 12:14.) For the Greek present in the sense of an intention see 1 Corinthians 16:5. CBSC
Either Paul is anticipating his third visit to Corinth, OR it was the thrid time that he had taken up thoughts of traveling and was nor preparing for such a journey. (Poole, etc.)
Paul’s first visit to Corinth was the founding visit recorded in Acts 18:1-18 . His second visit was the Painful visit noted in 2 Corinthians 1:23 - 2 Corinthians 2:1. The third visit will be the one coming up, which is accounted for in Acts 20:2-3. That Paul considers three to be significant is made clearer in the citation of Deuteronomy 19:15 which follows.- CPNT
Every charge will be established -- That is, he will hold a formal enquiry in the strict legal way (see reff.) when he arrives. No evasions will be possible. - Exp-GR
two or three witnesses -- The warning is made by quoting Deuteronomy 19:15.
But in regard to its application here, commentators are not agreed. Some suppose that Paul refers to his own epistles which he had sent to them as the two or three witnesses by which his promise to them would be made certain; that he had purposed it and promised it two or three times, and that as this was all that was required by the Law. BN
Lightfoot supposes that he refers to Stephanas, Fortunatus, and Achaicus, who would be witnesses to them of his purpose; see 1 Corinthians 16:17.
But the more probable opinion, it seems to me, is that of Doddridge, Macknight, and others, that he anticipated that there wound be necessity for the administration of discipline there, but that he would feel himself under obligation in administering it to adhere to the reasonable maxim of the Jewish Law. No one should be condemned or punished [ex-communicated] where there was not at least two or three witnesses to prove the offence. But where there were, discipline would be administered according to the nature of the crime. - BN