Proverbs 30:10 (ESV)

10 Do not slander a servant to his master, lest he curse you, and you be held guilty.

We may and should give ill reports of a person to those in authority over him, when such reports are true and warranted. If we neglect to speak the truth in love in such circumstances, we are being irresponsible. However, it is never right to slander someone. It is wrong and self-defeating for a man to tell harmful lies about someone to his master. Because a principled man in authority will investigate not only the slander, but also the slanderer, who may have the spoken curse of the innocent servant rightly placed against him. It will be by the faithful scrutiny of one’s master, not by the slanders of busybodies, that a man will eventually stand or fall.