'Sackcloth' in the Bible

"Alas for thee, Chorazin!" He cried. "Alas for thee, Bethsaida! For had the mighty works been done in Tyre and Sidon which have been done in both of you, they would long ere now have repented, covered with sackcloth and ashes.

"Alas for thee, Chorazin! Alas for thee, Bethsaida! For had the miracles been performed in Tyre and Sidon which have been performed in you, long ere now they would have repented, sitting in sackcloth and ashes.

When the Lamb broke the sixth seal I looked, and there was a great earthquake, and the sun became as dark as sackcloth, and the whole disc of the moon became like blood.

And I will authorize My two witnesses to prophesy for 1,260 days, clothed in sackcloth.