John Chrysostom
What does "in the fullness of blessing" mean? The Apostle is speaking either of possessions or, in general, of every good work. He customarily calls almsgiving a blessing, as he does many other things. For example, he says, "as a blessing, and not as covetousness" (2 Cor 9:5). Even in the Old Testament it was customary to call almsgiving by this name. But since the Apostle added here "of the Gospel," we affirm that by blessing he means not possessions alone, but all the rest as well. It is as though he says: I know that when I come to you, I shall find you prosperous in everything. You will be abounding in good things and worthy of many good praises, according to the Gospel. This is a wondrous way of giving counsel: to anticipate them with praises. Since the Apostle avoids presenting his thought in the form of exhortation, he undertakes this manner of correction.