Laws of Lashon Hara / 1: 5-6 (27)

5. One is forbidden to speak lashon hara, both out of his own desire or if he is urged to do so by another. Even if one of his parents, or his Rabbi, urge him to speak something that may be derived as any form of lashon hara, he is forbidden to do so.

6. One who refuses to speak lashon hara, even if this may cause a loss to his livelihood, such as him losing his job, he is still forbidden to speak lashon hara.