The Medrash (Rabbaj 16:2) states that the word “toras” is used five times in relation to someone who has tzora’as. This teaches us that one who speaks lashon hara (which causes tzora’as) is considered to have transgressed all five books of the Torah.
Sefer Sifsei Tzadik explains that speaking lashon hara is a very severe sin because one who engages in such speech damages his mouth and his words. One’s power of speech is what distinguishes man from all other creations, as it is used to serve Hashem through Torah and tefillah. Therefore, ruining it is a very serious transgression.
He says that the way to rectify this blemish is through Torah study. This is as is stated (Chulin 89A), where the Gemara quotes the verse (Tehillim 58:2): “Ha’umnom ailem tzedek tidabeiru (is it true that You were silent about the righteousness that You should have spoken).” The word “umnom” can also mean “a job”, and the word “ailem” can mean “a mute”. The Gemara thus explains the verse by saying: “What is a person’s job in this world? To make himself like a mute (and refrain from excess speech). Does this mean that one should not speak words of Torah? No, as the verse continues: ‘About righteousness you should have spoken.’” This means that by speaking words of Torah, one can rectify damages done to his mouth through improper speech.
This is also seen from the Gemara (Eruchin 15B) that says: “Rav Acha bar Chanina said: (Negative) words have no tikkun. Rav Chama bar Chanina said: (Negative) words have a tikkun through words of Torah, as is stated (Mishlei 15:14): ‘The remedy for the tongue is the Tree of Life.” When one grabs onto Torah (the Tree of Life), he can rectify his mouth.
The Sifsei Tzadik adds: “I heard from the holy mouth of my grandfather, the Chidushei Harim zy”a in the name of Rav Bunim of Peshischa zy”a an explanation on the verse (Mishlei 12:18): ‘There is one who speaks like the jabs of a sword.’ He explained that the verse is asking why the power of speech is so strong that it can stab like a sword. The pasuk answers: ‘The tongues of the wise bring healing.’ It is saying that Hashem gave power to the words of wise men to enter the depths of the hearts of bnei Yisroel. This is why speech is so powerful. This is especially true about words of Torah. One can strengthen himself and rectify himself with words of Torah.”
