EXOD701 ... if one sees a person ask his friend to lend him money (which is a positive Torah commandment, derived from the pasuk: אִם־כֶּ֣סֶף תַּלְוֶ֣ה, “When you lend money” (Shemos 22:24), as the Rambam explains in Sefer Hamitzvos) or to do a different favor for him, and the friend declined to help him; or if one sees someone violate a negative commandment in the area of bein adam l’chaveiro, such as taking revenge or bearing a grudge (according to the Gemara's explanation in Yoma [23a] of what is included in the prohibitions of taking revenge and bearing a grudge) and disparages that person before others by telling them what he witnessed, then his words are considered lashon hara. Since the speaker was not harmed by this person (and informing others of the incident will not accomplish anything constructive on behalf of the affected party), it is considered lashon hara ro reveal this negative information to others. All this applies even if one witnessed the incident himself, and it was clear to him that the other person could have done the favor for his friend but declined to do so because of his mean-spiritedness.... even if someone else was denied the favor, and the speaker's sole intent in speaking about the other person is in order to uphold the truth, it is still forbidden. If the speaker himself was the one who was denied the favor, then it is forbidden all the more for him to disparage his fellow over this. If he violates this halakhah, not only does he transgress the prohibition of lashon hara, but he also transgresses the negative commandment of לֹֽא־תִטֹּר֙, “Do not bear a grudge” (Vayikra 19:18). If his intention in disparaging the other person is to take revenge by publicizing his mean-spiritedness, then he violates the negative commandment of לֹֽא־תִקֹּ֤ם, “Do not take revenge” (ibid), aside from violating the prohibition of lashon hara.