Charles Ellicott Commentary Jeremiah 6:26

"O daughter of my people, gird thee with sackcloth, and wallow thyself in ashes: make thee mourning, as for an only son, most bitter lamentation; for the destroyer shall suddenly come upon us." — Jeremiah 6:26 (ASV)

Wallow thyself in ashes.—This is also seen in Jeremiah 25:34 and Ezekiel 27:30. The common sign of mourning was to sprinkle dust or ashes on the head (2 Samuel 1:2; 2 Samuel 13:19; Joshua 7:6). This act, as seen in Jeremiah 25:34, Micah 1:10, and Job 2:8, indicated an even greater wretchedness and prostration.

This English verb belongs to a class of verbs that were once used reflexively but have now become intransitive. The word “Endeavour” provides another example.