Shemiras Halashon Halachos
Hilchos Lashon Hara, Opening – positive commands (3) Sometimes, lashon hara also involves transgressing the positive command (Vayikra 19:15), "Judge your fellow charitably." For example, if one saw one's fellow [do something] and can judge him unfavorably and say that he did an evil act, or favorably so that he did not necessarily do an evil action, it a positive Torah command to judge him favorably, so that it results in one's fellow not having done an evil deed. If someone speaks lashon hara instead of judging favorably, or believes lashon hara instead of judging favorably, he transgresses this positive command.
Hilchos Lashon Hara, Opening – positive commands (4) If one's fellow loses his livelihood because of this lashon hara, such as when one publicized that one's fellow is dishonest or unprofessional in his profession, one transgresses the positive command (Vayikra 25:35), "A stranger and a resident, and he shall live with you," and afterwards it writes, "Your brother shall live with you." This commands us to help Jews find a livelihood so they should not need charity, and how much more should one not cause him to lose his livelihood.