Augustine of Hippo — as excerpted in the Catena Aurea on Matthew 5:38-42

“(Serm. in Mont. i. 20.) That He commands, And from him that would borrow of thee, turn not away, must be referred to the mind; for God loveth a cheerful giver. (2 Cor. 9:7.) And every one that receives, indeed borrows, though it is not he that shall pay, but God, who restores to the merciful many fold. Or, if you like to understand by borrowing, only taking with promise to repay, we must understand the Lord’s command as embracing both these kinds of affording aid; whether we give outright, or lend to receive again. And of this last kind of shewing mercy it is well said, Turn not away, that is, do not be therefore backward to lend, as though, because man shall repay you, therefore God shall not; for what you do by God’s command cannot be without fruit.”