Musar for Shabbat 298:3

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 see the greatness of the hatred borne against the wicked. For aside from their being driven away from the table of the King of kings, the Holy One Blessed be He, as we find in Shabbath 149b: "You are righteous, O L-rd; evil will not dwell in Your dwelling place" — even at a time when the prophets and the saintly ones implore mercy for Israel, they have no desire at all to implore mercy for the wicked. To the contrary, they intimate in their prayer that they ask nothing at all for the wicked, as it is written (Psalms 125:14): "Do good, O L-rd, for the good ones and for the upright in their hearts."