II Corinthians 12:6-7

For though I might desire to boast, I will not be a fool; for I will speak the truth. But I refrain, lest anyone should think of me above what he sees me to be or hears from me. And lest I should be exalted above measure by the abundance of the revelations, a thorn in the flesh was given to me, a messenger of Satan to buffet me, lest I be exalted above measure.