Nindya - Slander
Speaking ill of others, which harms both the speaker and the one spoken of.
Nindya or slander damages community and reflects the speaker's own spiritual poverty. Speaking negatively of others, even truthfully, should generally be avoided.
One who slanders the Saints is like poison.
Negative speech creates negative karma for the speaker.
Guru Granth Sahib
Written about in
- What Sikhism says about doing no harm
Speaking ill of someone is counted as harm to the speaker as well as the subject. True remarks about another person's faults are still generally to be left unsaid.
- What Sikhism says about truth and lying
Nindya goes further and asks you to avoid speaking ill of others even truthfully. Most systems limit honesty by exempting kindness; this one limits honesty by protecting reputations, and that carries a real cost — it makes warning people about bad actors harder.