I made sackcloth also my garment - I put on sackcloth. This was often done as expressive of grief and sorrow. See Psalms 30:11, note; Psalms 35:13, note. Compare Isaiah 22:12; Daniel 9:3. In the case here referred to, this was an act of religion; an expression of penitence and humiliation.
And I became a proverb to them - A jest; a subject of derision; a by-word. They ridiculed me for it. Compare 1 Kings 9:7.