The reading is from St. Paul's Second Letter to the Corinthians 12:10-19

Brethren, for the sake of Christ I am content with weaknesses, insults, hardships, persecutions, and calamities; for when I am weak, then I am strong.

I have been a fool! You forced me to it, for I ought to have been commended by you. For I was not at all inferior to these superlative apostles, even though I am nothing. The signs of a true apostle were performed among you in all patience, with signs and wonders and mighty works. For in what were you less favored than the rest of the churches, except that I myself did not burden you? Forgive me this wrong!

Here for the third time I am ready to come to you. And I will not be a burden, for I seek not what is yours but you; for children ought not to lay up for their parents, but parents for their children. I will most gladly spend and be spent for your souls. If I love you the more, am I to be loved the less? But granting that I myself did not burden you, I was crafty, you say, and got the better of you by guile. Did I take advantage of you through any of those whom I sent to you? I urged Titus to go, and sent the brother with him. Did Titus take advantage of you? Did we not act in the same spirit? Did we not take the same steps?

Have you been thinking all along that we have been defending ourselves before you? It is in the sight of God that we have been speaking in Christ, and all for your upbuilding, beloved.