'Sackcloth' in the Bible

You have turned my mourning into dancing for me;You have taken off my sackcloth and clothed me with joy,

But as for me, when they were sick, my clothing was sackcloth (mourning garment);I humbled my soul with fasting,And I prayed with my head bowed on my chest.

When I made sackcloth my clothing [as one in mourning],I became a byword [a mere object of scorn] to them.