2 Corinthians 12:6-7

Even if I should choose to boast, I would not be a fool, because I would be speaking the truth. But I refrain, so no-one will think more of me than is warranted by what I do or say, or because of these surpassingly great revelations. Therefore, in order to keep me from becoming conceited, I was given a thorn in my flesh, a messenger of Satan, to torment me.