Chaff is the loose, outer covering on wheat and other grains that must be separated in the threshing and winnowing process. In the biblical times, grain was threshed or trampled, crushed, and beaten on outdoor threshing floors to separate the inedible parts of the grain (the chaff or sweepings) from the edible parts. Because chaff is very lightweight, it would generally be blown away by the wind as the grain is tossed in the air. By selling the sweepings with the wheat, merchants were cheating people.
6 that we may buy the poor for silver and the needy for a pair of sandals and sell the chaff of the wheat?”