Charles H. Spurgeon on Psalms 15:5

"He that putteth not out his money to usury." By usury is generally understood the gain of anything above the principal, or that which was lent, exacted only in consideration of the loan, whether it be in money, corn, wares, or the like. It is most commonly taken for an unlawful profit which a person makes of his money or goods. The Hebrew word for usury signifies biting. The law of God prohibits rigorous imposing conditions of gain for the loan of money or goods, and exacting them without respect to the condition of the borrower, whether he gain or lose; whether poverty occasioned his borrowing, or a visible prospect of gain by employing the borrowed goods. It is said in Exodus 22:25, 26, "If thou lend money to any of my people that is poor by thee, thou shalt not be to him an usurer, neither shalt thou lay upon him usury," etc. And in Leviticus 25:35, 36, 37, "If thy brother be waxen poor, and fallen into decay with thee, then thou shalt relieve him; yea, though he be a stranger, or a sojourner, that he may live with thee: take thou no usury of him," etc. This law forbids the taking usury from a brother that was poor, an Israelite reduced to poverty, or from a proselyte; but in Deuteronomy 23:20, God seems to tolerate usury towards strangers; "Unto a stranger thou mayest lend upon usury." By strangers, in this passage, some understand the Gentiles in general, or all such as were not Jews, excepting proselytes. Others think that by strangers are meant the Canaanites, and the other people that were devoted to slavery and subjection; of these the Hebrews were permitted to exact usury, but not of such strangers with whom they had no quarrel, and against whom the Lord had not denounced his judgments. The Hebrews were plainly commanded in Exodus 22:25, etc., not to receive usury for money from any that borrowed from necessity, as in that case in Nehemiah 5:5, 7. And such provision the law made for the preserving of estates to their families by the year of jubilee; for a people that had little concern in trade, could not be supposed to borrow money but out of necessity: but they were allowed to lend upon usury to strangers, whom yet they must not oppress. This law, therefore, in the strictness of it, it obligeth us to show mercy to those we have advantage against, and to be content to share with those we lend to in loss, as well as profit, if Providence cross them. And upon this condition, a valuable commentator says, It seems as lawful for me to receive interest for money, which another takes pains with, improves, but runs the hazard of in trade, as it is to receive rent for my land, which another takes pains with, improves, but runs the hazard of in husbandry." Alexander Cruden, 1701-1770.