Musar for Moed Katan 9:16

I have seen part of the explanation of this matter in the book, Nachal Kedumim, viz.: It is well known that all of G-d's punishment of a man is for his good, so that he be cleansed of his sins, and, sometimes, that he repent. Therefore, when the Temple stood and we had a Cohein who cleansed, if a man stumbled into the sin of lashon hara, the Holy One Blessed be He would bring upon him the punishment of plague-spots. And even so, He did not bring it immediately upon his body, but upon the beams of his house. And he himself would have to come to the Cohein and say to him that there appeared to him something like a plague-spot in the house. And the Cohein would exhort him to repent — "My son, plague-spots come only for lashon hara, etc.", as we find in Torath Cohanim — so that he should exert himself thereby to depart from the sin. And if he did not take this to heart, the Holy One Blessed be He would punish him yet further in this manner, as explained by Rambam at the end of the laws of tzara'ath-uncleanliness: "House tzara'ath is not in the order of nature, but was a sign and wonder in Israel to warn them against lashon hara. If one spoke lashon hara, the beams of his house would undergo a change. If he repented, the house would be cleansed, and if he persisted in his wickedness until the house were knocked down, the leather appurtenances in his house on which he sat and reclined upon would undergo a change. If he repented, etc. And if he persisted in his wickedness until they were burned, his skin would undergo a change, and he would become a leper. And he would be separated [from others] and exposed [as a leper] by himself, so that he not take part in the converse of the wicked, which is levity and lashon hara, etc." And there was great benefit in this punishment. For when he saw the greatness of his punishment and his disgrace, his having to sit solitary outside the [three] camps always, not being allowed to come even to the camp of Israel, and constantly proclaiming his grief to the populace so that they should pray [to the L-rd] to have mercy upon him (viz. Moed Katan 5a), and (Vayikra 13:45): "and 'Unclean! Unclean!' shall he cry," then, as a matter of course, he would be extremely humbled by his sin and would take it upon himself for the future to take great care against this bitter sin and to conciliate the one he spoke [lashon hara] about. And the Holy One Blessed be He in His [great] lovingkindness would send a cure for his tzara'ath, and the Cohein would go outside the camp to see if the plague-spot had healed, as it is written (Vayikra 14:3): "And the Cohein shall go outside the camp, and the Cohein shall see, if the plague-spot of leprosy is healed, etc.", and then he would proceed according to the whole order written in the parshah concerning sprinkling and shaving, and afterwards, he [the Cohein] would bring his sacrifices for him.