Adam Clarke on 2 Corinthians 9:14

The exceeding grace of God in you - By the ὑπερβαλλουσαν χαριν, superabounding or transcending grace, of God, which was in them, the apostle most evidently means the merciful and charitable disposition which they had towards the suffering saints. The whole connection, indeed the whole chapter, proves this; and the apostle attributes this to its right source, the grace or goodness of God. They had the means of charity, but God had given these means; they had a feeling, and charitable heart, but God was the author of it. Their charity was superabundant, and God had furnished both the disposition, the occasion, and the means by which that disposition was to be made manifest.