Musar על ברכות 15:13

And we find also in Tanna d'bei Eliyahu 16: "Those who smite in secret 'i.e., speakers of lashon hara] and desecrators of the Name in the open and those who cheapen their friends with words, and those who instigate quarrels will, in the end, be like Korach [and his congregation] of whom it is written (Bamidbar 16:33): "And the earth covered them up." And sometimes the punishment for the sin of lashon hara, the gravest sin of all, is askarah [diphtheria], the gravest death of all, as Chazal have said (Berachoth 8a): "Nine hundred and three types of death were created in the world … askarah is the gravest of all." A sign is given here for all who enter the world, that their punishment is indicative of their sin, as stated in Shabbath 33b: The Rabbis taught: "Why does this death (askarah) begin in the intestines and end in the mouth? R. Yehudah b. Ilai answered: "Though the kidneys counsel, the heart deliberates and the tongue formulates, it is the mouth which consummates [the lashon hara]."