'Ashes' in the Bible

Daughter of my people, put on sackcloth and roll in ashes. Mourn with bitter wailing, as one mourns at the death of an only son. For the destroyer will come on us suddenly.

The whole valley of dead bodies and ashes and all the fields as far as the Brook Kidron to the corner of the Horse Gate toward the east will be holy to the LORD. It won't be uprooted or overthrown again, forever."