For to their power - To the utmost of their ability.
I bear record - Paul had founded those churches and had spent much time with them. He was therefore well qualified to bear testimony in regard to their condition.
Yea, and beyond their power - Beyond what could have been expected; or beyond what it would have been thought possible in their condition. Doddridge remarks that this is a noble hyperbole, similar to that used by Demosthenes when he says, “I have performed all, even with an industry beyond my power.” The sense is, they were willing to give more than they were well able. It shows the strong interest which they had in the subject, and the anxious desire which they had to relieve the needs of others.
Of themselves - (αὐθαίρεται authairetai). Acting from choice, self-moved, voluntarily, of their own accord. They did not wait to be urged and pressed to do it. They rejoiced in the opportunity of doing it. They came forward of their own accord and made the contribution. “God loveth a cheerful giver” 2 Corinthians 9:7; and from all the accounts which we have of these churches in Macedonia it is evident that they were greatly distinguished for their cheerful liberality.