Gaster's Exempla (1924), No. 104, tells a quiet parable with a sharp edge.
A man decided to cheat on his tithe. The Torah commands the Israelite to give a tenth of the field's yield — to the Levite, the priest, or the poor, depending on the year. This farmer, not wanting to part with so much, began setting aside less than the required tenth. A little smaller each year. A little more kept for himself.
Strangely, his harvest shrank each year too. What had been a hundred bushels became ninety, then eighty, then sixty. The slide continued until the yield of his field was only a tenth of what it had been when he first began cheating.
His friends heard and started offering ironic congratulations. "Mazel tov," they said, meeting him in the market. "You have finally become a priest. You now receive only the tenth — and God receives the other nine. You wanted to shrink God's share; you shrank your own until God was the landlord and you were the kohen collecting the tithe off your own field."
The joke has the bite of rabbinic ethics. What you refuse to give with a full hand, Heaven will collect from you a different way. Generosity is not a tax; it is the grammar of abundance. Withhold the tenth, and one day you will discover the nine were never really yours in the first place.