The Shepherd of Hermas is an anonymous early Church writing, probably composed in Rome around AD 140. It consists of a series of pictures or revelations made to a character named Hermas, which are then interpreted to him by an angel (called the Shepherd) or by an ageless woman representing the Church.
One of these pictures is an allegory of generosity and how it benefits both the giver and the receiver in equal measure - which is what God intended in the first place. I have abridged it slightly, as the original is rather wordy, and modernised some of the phrasing to make it more readable.
As I was walking in the field, I observed an elm and a vine. As I considered them and their fruits, the Shepherd appeared to me and said: "These are intended as an example for the servants of God.
"The vine produces fruit; the elm is an unfruitful tree. But unless the vine is supported by the elm, it cannot bear much fruit, and the fruit which it does bear is rotten because it trails along the ground. Therefore, when the vine is cast upon the elm, it yields fruit, both from itself and from the elm.
"This is a similitude for the poor man and for the rich." "How so, sir?" said I; "explain the matter to me." "Listen," he said: "The rich man has much wealth, but is poor in matters relating to the Lord, because he is distracted about his riches; he offers very few intercessions to the Lord, and those which he does offer are small and weak, and have no power above. The poor man, with fewer distractions and greater needs, is often in prayer, and his intercession has great power with God.
"So, when the rich man refreshes the poor, and assists him without hesitation in his necessities, the poor man (being helped by the rich) intercedes for him, giving thanks to God for the one who bestowed gifts upon him. This moves the rich man to continue to interest himself zealously for the poor man, that his wants may be constantly supplied. For he knows that the intercession of the poor man is acceptable and influential with God, and by it he (the rich man) is blessed.
"Thus, both accomplish their work, and it is a great work, acceptable before God. Poor men, interceding with the Lord on behalf of the rich, increase their riches; and the rich, again, aiding the poor in their necessities, satisfy their souls. Both, therefore, are partners in the righteous work."