'Earth Upon His Head' in the Bible

Behold, there came a man the third day out of the host from Saul with his clothes rent and earth upon his head. And when he came to David, he fell to the earth and did obeisance.

When David was come to the top of the mount and had bowed himself unto God: behold, Hushai the Archite came against him with his coat torn and earth upon his head.