Musar על סוטה 69:13

We also find that the spies, because of the sin of lashon hara, died an unnatural death, as it is written (Sotah 35a) (Bamidbar 14:37): "And they died, the men who had uttered an evil report of the land, etc." R. Shimon b. Lakish said: "They died an unnatural death." And it is stated there in the Gemara: "We are hereby taught that their tongues descended to their navels, and worms left their mouths onto their tongues, and from their tongues they descended to their navels."