I have ofttimes said, that almsgiving hath been introduced not for the sake of the receivers, but of the givers, for the latter are they which make the greatest gain. And this Paul shows here also. In what way? The Philippians had sent him somewhat, after a long time, and had committed the same to Epaphroditus. See then, how when he is about to send Epaphroditus as the bearer of this Epistle, he praises them, and shows that this action was for the need, not of the receiver, but of the givers. This he doth, both that they who benefited him may not be lifted up with arrogance, and that they may become more zealous in well-doing, since they rather benefit themselves; and that they who receive may not fearlessly rush forward to receive, lest they meet with condemnation. For “it is more blessed,” He saith, “to give than to receive.” (Acts 20:35.) Why then does he say, “I rejoice in the Lord greatly”? Not with worldly rejoicing, saith he, nor with the joy of this life, but in the Lord. Not because I had refreshment, but because ye advanced; for this is my refreshment.
St. John Chrysostom, Homily XV on Philippians 4:10-14, Homilies on Philippians, Colossians, and Thessalonians.