Leviticus 13:45 - Matthew Poole's English Annotations on the Holy Bible

His clothes shall be rent, to wit, in the upper and former parts, which were most visible. This was done, partly, as a token of sorrow, Ezra 9:3,5 Job 2:12, because though this was not a sin, yet it was an effect of sin, and a sore punishment, whereby he was cut off both from converse with men, and from the enjoyment of God in his ordinances; partly, as a warning to others to keep at a due distance from him wheresoever he came; and partly, as some add, that it might conduce to his cure, by giving the freer vent to the ill humours. But the exposing of the affected part to the cold would rather hinder than further evaporation. His head bare; another sign of mourning, as appears from Leviticus 10:6. God would have men, though not overwhelmed with, yet deeply sensible of, his judgments. A covering upon his upper lip; partly as another badge of his sorrow and shame, as Ezekiel 24:17,22 Mic 3:7; and partly for the preservation of others from his infectious breath or touch. Unclean, unclean; as begging the pity and prayers of others, and confessing his own infirmity, and cautioning those who came near him to keep at a distance from him.