speak evil

See: defame
References in classic literature ?
O whoreson scoundrel, how ungrateful you are, you see yourself raised from the dust of the earth to be a titled lord, and the return you make for so great a benefit is to speak evil of her who has conferred it upon you
The 'Keeping Up With The Kardashian' star had recently posted a selfie on the social networking site with a caption that read that one should neither see evil, hear evil nor speak evil.
Be an upright person, a just and true person, a patient and kind person, a person content with life, a person who can rejoice and not speak evil.
Those who have the least will have the best chance to flourish in an environment free from daily assault by employers and occupying forces, neighbors and those who speak evil of them.
He went on: "You speak evil about Osama because it suits you, your country and its political ambitions.
Across the country, both before and after Santana, similar warning signs--ranging from menacing e-mails to bomb diagrams to guns at school--have come to light before they turned into deadly disasters (see "See Evil, Hear Evil, Speak Evil," News and Trends, 3/19/01).
58] Never one to shrink before authority -- "non istima persona" -- the narrator threatens to use his "arte" to malign any one who tries to "threaten or intimidate him" [59] even as he appears to dismiss that threat: "but let whomever wishes speak evil [of the play].