Bible Dictionary
Dust
Dust consists of small particles of earth and is a biblical reminder of human frailty and mortality. Casting, sitting in, or sprinkling dust could express mourning, humiliation, abhorrence, or renunciation.
Biblical Usage
People cast dust on their heads in mourning, sat or lay in dust in affliction, and licked dust as a sign of submission. Shaking dust from the feet signified renunciation. Throwing dust expressed abhorrence, while dust could also symbolize an innumerable multitude.
Scripture References