Musar zu Mischlej 12:20

Chazal have explained that the class of slanderers is one of four classes who do not behold the Shechinah, viz. (Sotah 42b): "R. Yirmiyah b. Abba said: Four classes do not behold the Shechinah: the class of flatterers, the class of liars, the class of scoffers, and the class of slanderers … The class of slanderers, viz. (Psalms 5:5): 'For You are not a G-d that desires wickedness; evil will not sojourn with You.' You are righteous, O L-rd; evil will not sojourn in Your dwelling place.'" This section deals with the sin of lashon hara, as Rashi explains there. And the speaker of lashon hara is even called "evil," as we find in Aggadath Mishlei on the verse (Mishlei 12:20): "There is deceit in the heart of plotters of evil" — R. Chamma b. R. Chanina said: "One who speaks with his friend and eats and drinks with him and speaks lashon hara against him, the Holy One Blessed be He calls him 'evil,' etc." He is also judged in the fourth level of Gehinnom for this sin, as stated in Midrash Hane'elam on Ruth.

And it is found that it [(guarding one's tongue)] leads to peace [shalom]. And the greatness of peace is already known. As Chazal have said: "Even if there be, G-d forbid, the sin of idolatry in Israel, but there is peace among them, the Holy One Blessed be He tells Satan not to touch them." And if one accustoms himself to speak well of his friend, he merits that the Holy One Blessed be He calls him by His name — "Shalom!" As it is written (Judges 6:24): "And he called it [(the altar)] 'the L-rd - Shalom.'" And if he does the opposite, G-d forbid, he is called "Ra" ["evil"]. As Chazal have said: "If one speaks with his friend and eats with him and drinks with him and speaks lashon hara against him, the Holy One Blessed be He calls him 'Ra,' as it is written (Mishlei 12:20): 'There is deceit in the heart of the plotters of ra.' And if one does not eat and drink with him and does not deal with him [i.e., if he has acquired no favors from him] and [still] he speaks well of him, the Holy One Blessed be He calls him 'Shalom,' viz. (Ibid.): 'And for the counselors of Shalom there is joy.'"

And of these twenty-four things that impede repentance, five of them are such that he who does them is constantly drawn after them and finds it very difficult to separate himself from them. Therefore, a man must be very careful of these, lest he cleave to them, and they are all very evil states of mind. And these are : tale-bearing, gossip, wrath, evil thoughts, and associating with a wicked man, for he will surely learn from his deeds. For when one is always with the wicked and sees these deeds they become impressed in his heart, as Solomon said, "But the companion of fools shall smart for it" (Prov. 12:20).