They eat up the sin of my people, and they set their heart on their iniquity.
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Cyril of Alexandria
They used to sacrifice goats for sin; for this reason the sacrifice was called sin. By offering a goat on the altar, the priests at the right time used to bring the intestines and the lard, and they ate the rest. This was ordered by the divine law. … “They eat the sins of my people” means they eat the offerings brought for sins.
Sins: victims. (Worthington)
Iniquity; or "they seek for support in their propitiatory offerings "and lull the people asleep in their sins. The priests of the golden calf imitated the sacred rites of Moses. It would have been too difficult to make the people change altogether.
[The priests] are feasting on the sins of my people, approving the crimes of the sinners. For when they behold them sinning, not only do they not argue but they praise and extol them, calling them fortunate.