2 Corinthians 8:3
“For according to their power, I bear witness.” Trustworthy is the witness. “And beyond their power.” That is, it “abounded unto the riches of their liberality.” Or rather, he makes this plain, not by this expression alone, but also by all that follows; for he says, “of their own accord.” Lo! Yet another excessiveness.
Source: Homilies on Second Corinthians (New Advent)