"Tzara'as was the punishment for the sin of [Tsismis]."
"This shall be the law of the metzora" [Metzora 14:2].
Why, asked R' Shmuel of Sochotchov, does the verse state: "This shall be the law of the metzora" and not "This is the law of the metzora"?
The tzara'as affliction, answered the Rebbe, is brought about by the sin of haughtiness. Once he is afflicted, however, and individuals begin to distance themselves from him, he feels contrite and humbled.
But this feeling of humility must accompany him for the rest of his life. Even after he is healed, let him not return to his previous state of arrogance; rather, he must ingrain the lesson he has learned as a metzora and remain humble until his very last day. — Lessons to be learned