'Sackcloth' in the Bible

Woe to thee, Chorazin! woe to thee Bethsaida! for if the works of power which have taken place in you, had taken place in Tyre and Sidon, they had long ago repented in sackcloth and ashes.

Woe to thee, Chorazin! woe to thee, Bethsaida! for if the works of power which have taken place in you had taken place in Tyre and Sidon, they had long ago repented, sitting in sackcloth and ashes.

And I saw when it opened the sixth seal, and there was a great earthquake; and the sun became black as hair sackcloth, and the whole moon became as blood,

And I will give power to my two witnesses, and they shall prophesy a thousand two hundred and sixty days, clothed in sackcloth.