I made sackcloth also my garment; and I became a proverb to them.
Read Chapter 69
Augustine of Hippo
14. "And I have set sackcloth my garment" (ver. 11). Already before we have said something of the sackcloth, from whence there is this, "But I, when they were troubling Me, was covering myself with sackcloth, and was humbling My Soul in fasting. I have set sackcloth for My garment:" that is, have set against them My flesh, on which to spend their rage, I have concealed My divinity. "Sackcloth," because mortal the flesh was: in order that by sin He might condemn sin in the flesh. "And I have set sackcloth my garment: and I have been made to them for a parable," that is, for a derision. It is called a parable, whenever a comparison is made concerning some one, when he is evil spoken of. "So may this man perish," for example, "as that man did," is a parable: that is, a comparison and likeness in cursing. "I have been made to them," then, "for a parable." ...
Hair-cloth. The sacred humanity, which being torn, let out the price of our redemption. (St. Augustine) (Menochius)
I mourned for my country (Calmet)
Christ was clothed in derision, with a soldier's straight purple garment. (Berthier)