Sackcloth was Worn by Persons in Affliction
Source: TTT
Nehemiah 9:1
On the twenty-fourth day of the same month, the Israelites gathered together, fasting and wearing sackcloth, with dust on their heads.
Psalm 69:11
I made sackcloth my clothing, and I was sport to them.
Jonah 3:5
And the Ninevites believed God. They proclaimed a fast and dressed in sackcloth, from the greatest of them to the least.