Genesis 37:34

Sack-cloth, or hair-cloth, cilicio. These garments were made very close, like a sack, of the hair taken from the goats of Cilicia, which grew long, rough, and of a dark colour. The poorest people used them: Usum in Castrorum & miseris velamina nautis, (Vir.[Virgil,?] Geor. 3.); and the Ascetics, or monks, afterwards chose them for the sake of mortification and humility. (Calmet) --- Jacob was the first, mentioned in Scripture, who put them on, and the Israelites imitated him in their mourning. --- Long time; twenty-three years, till he heard of his son being still alive. (Menochius)