31. This solemn asseveration refers to what follows. The persecution at Damascus was one of the first and greatest, and having no human witness of it to adduce to the Corinthians, as being a fact that happened long before and was known to few, he appeals to God for its truth. Luke (Ac 9:25) afterwards recorded it (compare Ga 1:20), [BENGEL]. It may ALSO refer to the revelation in 2Co 12:1, standing in beautiful contrast to his humiliating escape from Damascus.