Дварим 27:24 Галаха: Chafetz Chaim

How great is the issur of lashon hara, which the Torah has forbidden even if true and in all modes. For not alone if he is careful to speak it only in private and to insist that it not be revealed to him [who is spoken about] is it forbidden, [for through this he also brings a curse upon himself, viz. (Devarim 27:24): "Cursed be he who smites his neighbor in secret"], but even if he knows that he would speak it even to his face, or actually speaks lashon hara to his face, even so it is forbidden and called "lashon hara." And in one respect, the issur is greater "to his face" than not to his face." For in his presence, aside from the issur of lashon hara, he [the speaker] clothes himself with the trait of brazenness and audacity, and arouses more strife thereby. And very often this leads also to the "whitening of (the other's) face (in shame)," as we have enlarged upon in the introduction concerning the negative commandment of (Vayikra 19:17): "Do not bear sin because of him."

And now we shall explain, with the help of the L–rd, what we projected in the beginning, to detail how many arurin he who does not guard himself against this evil trait beings upon himself. (1) Aside from all the aforementioned negative and positive commandments, he transgresses (Devarim 27:24): "Cursed be he who smites his neighbor in secret," which refers to lashon hara, as we find in Sifrei and in Rashi's commentary on Chumash.

And, aside from this, how can the hoped-for blessings of the Holy One Blessed be He repose upon us when, in our many sins, we have become habituated to this sin? Is there not an explicit curse on this in the Torah, viz. (Devarim 27:24): "Cursed is he who strikes his neighbor in secret," which refers to lashon hara, as Rashi explains there (aside from the other curses which are superadded to this, as will be shown at the end of this preface)?