Musar su Salmi 50:20

Chazal have said (Sanhedrin 26b) that the Holy One Blessed be He said to Doeg, the wicked one: "When you reach the section concerning the speakers of lashon hara, what do you expound?" The meaning is: When a man commits a transgression, by nature he is ashamed and aggrieved to come upon the relevant section in the Torah. Because of this Eliyahu Rabbah writes (end of 138): "One who is blind or lame should not be called to the Torah for the section [that discusses these defects]. Similarly, one who is suspect of illicit relations should not be called for that section, or the like." If so, in our instance, we have demonstrated above that a great portion of the Torah speaks of these things [(lashon hara)] and a man who broadens his lips and abandons his speech in whichever direction his yetzer desires, will certainly in the course of his life transgress each thing many tens of times, and how his soul will storm when they show him in time to come that in the few days of his life he has transgressed many tens of sections in the Torah. It is known what Chazal (Chagigah 5b) have said on the verse (Amos 4:13): "For He that forms the mountains and creates the winds and tells a man what his speech is"— "even a man's lightest converse is related to him at the time of his judgment." How much more so will he be reproved for these grave forbidden matters [of lashon hara] and have them laid before his eyes, as it is written in Psalms 50:20: "You sit and speak against your brother. Against your mother's son you utter slander …but I will reprove you and set it in order before your eyes." And it is known what the GRA has written, that for every utterance of forbidden speech (such as lashon hara and rechiluth and the like) one must descend to the very depths of Sheol, and it is impossible to visualize the throes and afflictions one suffers for one such utterance.

And we learn in Devarim Rabbah: "R. Chaggai said: Plague-spots come only for lashon hara. The Rabbis said: Know this to be true, for Miriam the tzaddeketh, because she spoke lashon hara against Moses her brother, plague-spots came upon her, as it is written (Devarim 24:9): 'Remember what the L-rd your G-d did to Miriam on the way when you went out of Egypt.' And this is the intent of the verse (Psalms 50:20): 'You sit and speak against your brother; against your mother's son you utter slander.' R. Yehoshua b. Levi explained: "If you have taught your tongue to speak against your brother from your father, but not from your mother, in the end, "against [even] your mother's son you will utter slander." For whoever presumes to speak [slander] against him who is greater than he, causes evil to himself, plague-spots drawing near to him. And if you do not believe this, Miriam the tzaddeketh is the paradigm for all the speakers of lashon hara — 'Remember what the L-rd your G-d did to Miriam, etc.' R. Shimon said: Now if with Miriam the tzaddeketh, who did not intend to speak lashon hara, but who spoke for the good of her brother, this [was the result], then those evildoers, whose intent it is to speak lashon hara against their neighbors to cut off their lives, how much more so will the Holy One Blessed be He cut off their tongues, as it is written (Psalms 12:4): 'The L-rd will cut off all the slippery [i.e., slanderous]lips.'"

There is a general way to rescue oneself from this bitter sin and its punishment. And this is what we are taught by the Blessed L-rd in Parshath Tetze (Devarim 24:8): "Guard yourself against the plague-spot of leprosy, to take great care and to do according to all that the Cohanim teach you, etc.", followed by (Ibid. 9): "Remember what the L-rd your G-d did to Miriam on the way when you went out of Egypt." And we learned in Sifrei: "Remember what the L-rd your G-d did" — I might think, [remember] in your heart, but 'Guard yourself against the plague-spot of leprosy to take care and to do' already speaks of the guarding of the heart (For the Sifrei understands "Guard yourself in [lit.], the plague-spot of leprosy" as "from the plague-spot of leprosy"; that is, that we not divert our heart from guarding against the sin [lashon hara], which leads to it). How, then, am I to fulfill 'Remember'? Mention it with your mouth." The will of the Torah, then, is that we remember the greatness of the punishment of this bitter sin both in the heart and by the mouth in order to avail our souls by this. As Ramban wrote in Mitzvah 7 of his Mitzvoth: "We have been commanded to remember by the mouth and return it to our heart, what the exalted L-rd did to Miriam when she spoke against her brother, though she was a prophetess, in order to distance ourselves from lashon hara and not be one of those of whom it is said (Psalms 50:20): "You sit and speak against your brother; against your mother's son you utter slander." For, in truth, the remembrance of the issur and the greatness of its punishment lead to guarding against it, just as the remembrance of the positive commandments leads to their fulfillment, as it is written (Bamidbar 15:40): "And you shall remember all the mitzvoth of the L-rd and you shall do them."