'Sackcloth' in the Bible

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

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!

And I watched when he opened the sixth seal, and a great earthquake took place, and the sun became black like sackcloth made of hair, and the whole moon became like blood,

And I will grant [authority] to my two witnesses, and they will prophesy [for one] thousand two hundred sixty days, dressed in sackcloth."