The ashes of a red heifer burned entire ( Numbers 19:5 ) when sprinkled on the unclean made them ceremonially clean ( Hebrews 9:13 ).

To cover the head with ashes was a token of self-abhorrence and humiliation ( 2 Samuel 13:19 ; Esther 4:3 ; Jeremiah 6:26 , etc.).

To feed on ashes ( Isaiah 44:20 ), means to seek that which will prove to be vain and unsatisfactory, and hence it denotes the unsatisfactory nature of idol-worship. (Compare Hosea 12:1 ).

These dictionary topics are from
M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition,
published by Thomas Nelson, 1897. Public Domain, copy freely.