The God and Father of our Lord Jesus Christ, which is blessed for evermore, knoweth that I lie not.

People's New Testament

11:31 The God and Father... knoweth that I lie not. He has given as astonishing catalogue of suffering. Yet, God knows that every word is true.

Jamieson-Fausset-Brown Bible Commentary

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.

Matthew Henry's Concise Commentary

11:22-33 The apostle gives an account of his labours and sufferings; not out of pride or vain-glory, but to the honour of God, who enabled him to do and suffer so much for the cause of Christ; and shows wherein he excelled the false apostles, who tried to lessen his character and usefulness. It astonishes us to reflect on this account of his dangers, hardships, and sufferings, and to observe his patience, perseverance, diligence, cheerfulness, and usefulness, in the midst of all these trials. See what little reason we have to love the pomp and plenty of this world, when this blessed apostle felt so much hardship in it. Our utmost diligence and services appear unworthy of notice when compared with his, and our difficulties and trials scarcely can be perceived. It may well lead us to inquire whether or not we really are followers of Christ. Here we may study patience, courage, and firm trust in God. Here we may learn to think less of ourselves; and we should ever strictly keep to truth, as in God's presence; and should refer all to his glory, as the Father of our Lord Jesus Christ, who is blessed for evermore.