Shemirat HaLashon שמירת הלשון

It is written (Vayikra 19:16): "Do not go talebearing among your people." This negative commandment includes both rechiluth and lashon hara, as we find in Yerushalmi. [Rechiluth (talebearing)] is one's saying to his friend: "Ploni said this about you" or "did this and this to you." Lashon hara is one's telling his friend something demeaning of another, or other things which cause him (the other) bodily, monetary, or emotional harm.] And this negative commandment also includes lashon hara, as our sages of blessed memory have said in explanation of this verse: "Do not be as a merchant [rochel], who takes his wares from one to another." And it is known that this negative commandment obtains even if what is said is the truth, as all of the commentators have written. For if it is false, it is in the category of motzi shem ra [giving out a bad name], and is far more severe than lashon hara in general. Preceding the aforementioned verse is [Ibid. 15): "…In righteousness shall you judge your neighbor," concerning which our sages of blessed memory have said (Avoth 1:5): "Judge every man in the scales of merit." This also applies to our subject, implying that even if you see something demeaning in him, still you must seek some merit in him, viz.: Perhaps he spoke or did this thing unwittingly, or he did not know that it is forbidden to do or say this thing, or perhaps he has already regretted [what he did or said], and the like. Therefore, Scripture commanded that you not bear tales about him and not tell others the demeaning things that you know about him. All the details of lashon hara and rechiluth, and the greatness of the reward of him who takes care to avoid it, and the punishment for the transgressor are explained in Chafetz Chaim and Shemirath Halashon, Chapter I.

(Ibid. 16): "You shall not stand by the blood of your neighbor," which Rashi explains: "to watch him die, if you are able to save him, as in the instance of one drowning in the river or being attacked by animals of robbers." See Sanhedrin 73a, to the effect that if he cannot save him himself, he must exert himself to hire others to save him. This precedes "Do not go talebearing," apparently to teach us that if he transgressed by severe rechiluth against a man, injecting great anger in the heart of Ploni against him to the extent of endangering his life, [(as Doeg did before Saul against David)], he must thereafter see to it to remove the danger. And if he cannot do so by himself, he must get others to try to save him. The verse concludes; "I am the L-rd," which Rashi understands as "trusted to reward" one who is careful to avoid rechiluth and who exerts himself to save his friend from danger, and "trusted to exact punishment" of one who does the opposite, as we find in Peah 1:2: "For three transgressions punishment is exacted of a person in this world, with the principal remaining for him [for punishment] in the world to come: idolatry, illicit relations, murder — and lashon hara over and against all."

(Ibid. 17): "Reprove shall you reprove your neighbor, but do not bear sin because of him"; that is, do not "whiten his face" in public, even by way of reproof; how much more so, otherwise. If one whitens the face of his friend in public, his sin is too great to bear. As we find in Bava Metzia 58b: "If one whitens his friend's face in public, it is as if he sheds blood." And (Ibid. 59a): "It is better for one to cast himself into a fiery furnace than to whiten his friend's face in public. Whence is this derived? From [the instance of] Tamar, viz. (Bereshith 38:25): 'She was taken out [to be burned], and she sent to her father-in-law, saying, etc.'" It is apparent from this that even if the man [spoken against] is, indeed, liable, still, great care must be taken not to shame him. And it emerges from the Gemara that if one is accustomed to whiten his friend's face in public, he has no share in the world to come.

(Vayikra 25:17): "And you shall not wrong, one man, his fellow.": Here, the Torah exhorted against verbal wronging; that is not to hurt his fellow with words. And, in Bava Metzia 58b: "Verbal wronging is worse than monetary wronging, for the first is directed against his person, and the second, against his possessions; and the second allows of restitution, whereas the first does not." And it is stated there: [With the destruction of the Temple,] "all the gates [to the L-rd] are locked except the gates of wronging." [i.e., they are open to the wronged one to cry out and] to exact punishment of the wronger. And verbal wronging also is in the category of lashon hara, as we find in Yoma 44a.