“Rabbi Shimon said: Just as Miriam, the Righteous, was punished though she did not have [any] intention to speak Lashon HaRa, but rather spoke for the sake of her brother, for his own good, those evildoers who intend to speak Lashon HaRa against others [in order] to cut into [and bring destruction to] their lives, how much more so will The Holy One, Blessed is He, cut off their tongues, as it says “HaShem will cut off all of the smooth lips [the tongue that speaks with import]”. (Tehillim: 12; 4)
[Another instance of afflictions coming upon the habitual speaker of Lashon HaRa is evident in the incident of the spies who spoke Lashon HaRa against the Land of Israel]. [These] spies died an unnatural death as a result of their sin of Lashon HaRa. [This follows that which our Sages of Blessed Memory have] said [in maseches Sotah (35a)]: “And the men who brought out evil slander about The Land died [in a plague, before HaShem].” (Bamidbar: 14; 37) Rabbi Shimon ben Lakish said that [the spies who spoke Lashon HaRa] died an unnatural death. [The Rabbis also] said in the [above] gemara: “[Rabbi Shimon said in the name of Rabbi Chanina the son of Pappa: Rabbi Sheila from the village of Timrata expounded [as follows]: [The fact that the pasuk notes “in a plague”] teaches [that] their tongues stretched out and fell on their navels, and worms were going out of their mouths, entering their tongues, and from their tongues were entering their navels.”
[Our Sages of Blessed Memory] have [taught] in [maseches] Arachin (15a), [as follows]: “Come and [take note of the] great [destructive] power of issuing a libelous report. From where [do we behold of the great damage caused by issuing a libelous report]? From the [incident involving the Motzi Shem Ra spoken by ten of the] spies [and their resulting punishment. The spies, by speaking] libelously against trees and stones [nevertheless suffered] such [a punishment of death, by falling victim to such a horrific plague, therefore], how much more so would one who speaks libelously against his fellow [be severely punished].
Based on the aforementioned, we can learn [of] the magnitude of the punishment [for speaking Lashon HaRa and Motzi Shem Ra. This sin is so severe], for a person is punished through afflictions as well as other types of punishments on account of these [sins. Realization of the severe punishments for speaking Lashon HaRa will enable] everyone to understand the tremendous good compensation for one who guards himself from this sin, [that good compensation] outweighing [the punishment of one who speaks Lashon HaRa and Motzi Shem Ra].
 This teaching can also be found in Bamidbar Rabba on Parshas “Ki Seitze” Parsha 6; 8-9.
 This translation is based on the MaLBI”M’s explanation of the verse.
 The commentators RaDa”L and MaHaRa”Z explain that “son of the mother” refers to a full sibling, whereas “son of the father” is a half brother. Therefore, if one begins to speak of a half-brother, who they have less love for, they will eventually come to speak against a full brother who they love more.
The RaDa”L explains that those brothers from the same father would argue with each other over the inheritance and are therefore more likely to speak Lashon HaRa against each other than against their brother from the mother. Nevertheless, they will eventually come to speak against their sibling from the mother as a result of the Lashon HaRa against their siblings from the father. MaHaRa”Z explains that we do not read “son of your mother” – “ben imcha” but rather “one of your nation” – “ben umaticha”. If one comes to speak Lashon HaRa against their “brother from their father” who is not Jewish, they will eventually come to speak against a member of their nation.
 For more information on this teaching, see sefer “Chofetz Chaim” - k'lal 8 in the B’air Mayim Chaim.
 The word “cut” - “חתך” - is used in both the phrases “those evildoers who have the intention to speak Lashon HaRa against others [in order] to damage (lit. cut) their lives” and “how much more so will The Holy One, Blessed is He, cut off their tongues”. We see from here that HaShem punishes the speaker of Lashon HaRa measure-for-measure. Just as he intended to damage someone else’s life, HaShem will cut off his tongue.
 Alternatively, “smooth lips” - “sifsei chalakos”, can be translated as “lips of division”.
 RaSh”I states that the verse writes the phrase "בּמגפה" – “in a plague” with a “patach” under the letter “beis” in the place of the “sheva”. The “patach” under the “beis” denotes a unique type of plague, especially fitting for the Lashon HaRa that the spies spoke against the Land of Israel. Since they sinned with their tongues, they were punished, measure for measure, by having their tongues stretched out to their navels with worms crawling from their mouths into their tongues and then into their navels. (Sotah, 35a) The gemara states that according to another opinion, ascara, commonly translated as “diphtheria” was the plague from which the spies suffered and died. Diphtheria is an upper tract respiratory ailment which is characterized by a sore throat.
 The reward for good actions is greater than the punishment for committing sins, as we see in Parshas “Ki Sisa” that HaShem “Guards kindness for thousands of generations… He visits the sins of the parents upon the children, grandchildren, third, and fourth generations.” (Shmos: 34, 7) HaShem rewards for thousands of generations, but punishes for a few generations; the reward being in much greater measure than the punishment.