Charles Ellicott Commentary 1 Kings 20:38

"So the prophet departed, and waited for the king by the way, and disguised himself with his headband over his eyes." — 1 Kings 20:38 (ASV)

Ashes upon his face. —It should be a “bandage over his head,” to cover his face, and to accord with the appearance of a wounded soldier. Unless the wound had some symbolic significance in application to Ahab or Israel, it is difficult to see what purpose it could serve.