Sin is a thing that writes itself across a man's face. It cannot be concealed. People talk sometimes of secret vices. There are no such things. If a wretched man has a vice, it shows itself in the lines of his mouth, the droop of his eyelids, the moulding of his hands even.
(כד) א֣וֹ בָשָׂ֔ר כִּֽי־יִהְיֶ֥ה בְעֹר֖וֹ מִכְוַת־אֵ֑שׁ וְֽהָיְתָ֞ה מִֽחְיַ֣ת הַמִּכְוָ֗ה בַּהֶ֛רֶת לְבָנָ֥ה אֲדַמְדֶּ֖מֶת א֥וֹ לְבָנָֽה׃ (כה) וְרָאָ֣ה אֹתָ֣הּ הַכֹּהֵ֡ן וְהִנֵּ֣ה נֶהְפַּךְ֩ שֵׂעָ֨ר לָבָ֜ן בַּבַּהֶ֗רֶת וּמַרְאֶ֙הָ֙ עָמֹ֣ק מִן־הָע֔וֹר צָרַ֣עַת הִ֔וא בַּמִּכְוָ֖ה פָּרָ֑חָה וְטִמֵּ֤א אֹתוֹ֙ הַכֹּהֵ֔ן נֶ֥גַע צָרַ֖עַת הִֽוא׃ (כו) וְאִ֣ם ׀ יִרְאֶ֣נָּה הַכֹּהֵ֗ן וְהִנֵּ֤ה אֵֽין־בַּבֶּהֶ֙רֶת֙ שֵׂעָ֣ר לָבָ֔ן וּשְׁפָלָ֥ה אֵינֶ֛נָּה מִן־הָע֖וֹר וְהִ֣וא כֵהָ֑ה וְהִסְגִּיר֥וֹ הַכֹּהֵ֖ן שִׁבְעַ֥ת יָמִֽים׃ (כז) וְרָאָ֥הוּ הַכֹּהֵ֖ן בַּיּ֣וֹם הַשְּׁבִיעִ֑י אִם־פָּשֹׂ֤ה תִפְשֶׂה֙ בָּע֔וֹר וְטִמֵּ֤א הַכֹּהֵן֙ אֹת֔וֹ נֶ֥גַע צָרַ֖עַת הִֽוא׃
(24) When the skin of one’s body sustains a burn by fire, and the patch from the burn is a discoloration, either white streaked with red, or white, (25) the priest shall examine it. If some hair has turned white in the discoloration, which itself appears to go deeper than the skin, it is leprosy that has broken out in the burn. The priest shall pronounce him unclean; it is a leprous affection. (26) But if the priest finds that there is no white hair in the discoloration, and that it is not lower than the rest of the skin, and it is faded, the priest shall isolate him for seven days. (27) On the seventh day the priest shall examine him: if it has spread in the skin, the priest shall pronounce him unclean; it is an affliction of tzara'at.
The tzara'at lesions which Scripture lists as rendering the victim unclean have nothing in common with the leprous diseases known to medicine. Tzara'at is a supernaturally caused affliction imposed by God on a person to punish her/him for a sin or to atone for a wicked deed.
...Back in ancient times when people got sick, they often thought that it was because of something they had done; they thought that it was direct punishment for moral sins. Knowing that, it's not surprising to learn the ancient sages' response to why people got afflicted with tzara'at. They took the word for the one who is afflicted --metzora--and turned it into a pun. They said that the metzora is the person who is motzi ra, someone who says bad things about other people.
(ב) אלו הדברים נפרעין מן האדם בעולם הזה והקרן קיימת לו לעולם הבא: על ע"ז ועל ג"ע ועל שפיכת דמים. ועל לשה"ר כנגד כולם.
For these [evil] things they collect interest from the person in this world and the principal (i.e. main punishment) remains for the World to Come: for idol worship, for illicit sexual relations, and for murder. And for gossip [the damage and punishment are] equivalent to them all.
Know that a word suddenly shot from the tongue is like an arrow shot from the bow. Son, that arrow won't turn back on its way; you must dam the torrent at its source.
Close your eyes. Picture the last mean, hurtful, or mocking name you called another person, whether to their face or in private to a third person. Try to see the word or phrase clearly in your mind. Turn it around and consider it.
Now picture the same word or phrase written in large letters across your forehead for all the world to see - in fact, this word or phrase, this blemish across your forehead, is the first thing people notice about you.
How would other people react to your blemish? Would it change how they treat you? What do you think you would need to do to clear your skin?