Paul then wrote the second letter to them from Macedonia, evidently dispatching it by the hand of Titus. Then, after a few months, his efforts to visit Corinth materialized. So Paul actually visited the Corinthians twice. After his first visit, at which time he established the congregation, he made a plan for a second visit, which failed. But “the third time” that he planned or got “ready” he was successful, for he was able to see them again in about 56 C.E. (2Co 1:15; 12:14; 13:1)

And he indicated that the principle in the Law of establishing every matter at the mouth of two or three witnesses applies in the Christian congregation. (De 19:15; 2Co 13:1)