When a person has been declared by the examining priest to have contracted tzara’at on his skin, he must dwell outside the city until the tzara’at disappears. This is appropriate corrective action for the antisocial gossip of which he was guilty. Tzara’at appears on the walls of a person’s home and on his garments before it appears on his skin.
Purging Negativity
וְהַבֶּגֶד כִּי יִהְיֶה בוֹ נֶגַע צָרָעַת וגו': (ויקרא יג:מז)
A garment that has the lesion of tzara’at on it . . . Leviticus 13:47

Our skin, clothing, and homes are three increasingly external layers that envelop us. Tzara’at first affected the outermost “garment,” the house, because at first, gossip is a totally superficial symptom. If the individual did not take this cue, neglecting to purge himself of his hidden negativity, tzara’at broke out on his clothing. This indicated that his hidden flaws had started to seep into him from the outside. If he ignored this cue as well, tzara’at broke out on his skin, indicating that his inner evil, although still superficial, was now part of him. At this stage, he had to be ostracized from society, with the hope that this demonstration of the consequences of his misbehavior would inspire him to mend his ways.1