II Corinthians 12:9-10
But he said to me, My grace is sufficient for you, for my power is made perfect in weakness. Therefore I will boast all the more gladly about my weaknesses, so that Christs power may rest on me. That is why, for Christs sake, I delight in weaknesses, in insults, in hardships, in persecutions, in difficulties. For when I am weak, then I am strong.
Galatians 4:13-15
As you know, it was because of an illness that I first preached the gospel to you, and even though my illness was a trial to you, you did not treat me with contempt or scorn. Instead, you welcomed me as if I were an angel of God, as if I were Christ Jesus himself. Where, then, is your blessing of me now? I can testify that, if you could have done so, you would have torn out your eyes and given them to me.
II Corinthians 10:10
For his letters, say they, are weighty and powerful; but his bodily presence is weak, and his speech contemptible.