'Sackcloth' in the Bible

“Woe to you, Chorazin! Woe to you, Bethsaida! For if the miracles that were done in you had been done in Tyre and Sidon, they would have repented in sackcloth and ashes long ago!

“Woe to you, Chorazin! Woe to you, Bethsaida! For if the miracles that were done in you had been done in Tyre and Sidon, they would have repented long ago, sitting in sackcloth and ashes!

Then I saw Him open the sixth seal. A violent earthquake occurred; the sun turned black like sackcloth made of goat hair; the entire moon became like blood;

I will empower my two witnesses, and they will prophesy for 1,260 days, dressed in sackcloth.”