Jonah 3:6
"For word came unto the king of Nineveh, and he arose from his throne, and he laid his robe from him, and covered him with sackcloth, and sat in ashes."
Cross References (ranked by relevance)
And he took him a potsherd to scrape himself withal; and he sat down among the ashes.
And I set my face unto the Lord God, to seek by prayer and supplications, with fasting, and sackcloth, and ashes:
Woe unto thee, Chorazin! woe unto thee, Bethsaida! for if the mighty works had been done in Tyre and Sidon, which have been done in you, they had a great while ago repented, sitting in sackcloth and ashes.
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 spoiler shall suddenly come upon us.
Woe unto thee, Chorazin! woe unto thee, Bethsaida! for if the mighty works, which were done in you, had been done in Tyre and Sidon, they would have repented long ago in sackcloth and ashes.
Say unto the king and to the queen, Humble yourselves, sit down: for your principalities shall come down, even the crown of your glory.
Declare ye it not at Gath, weep ye not at all: in the house of Aphrah roll thyself in the dust.
He putteth his mouth in the dust; if so be there may be hope.
Wherefore I abhor myself, and repent in dust and ashes.