Gravel

Gravel appears in scripture as a figure for the bitter aftermath of dishonest gain.

Bread of Falsehood

The proverb pairs initial sweetness with subsequent grit. "Bread of falsehood is sweet to a man; But afterward his mouth will be filled with gravel" (Prov 20:17). What goes down easily as bread comes to be experienced as something inedible — stones in the mouth. The figure works on the contrast between the moment of acquisition and the moment of consumption: the food obtained by deceit looks like bread, then turns to gravel between the teeth.