كلمة حق يراد بها باطل

Etymology
Literally: “A word of truth by which falsehood is intended”. Ascribed to Ali b. Abi Talib, who referred with it to the slogan used by the Kharijites after the Battle of Siffin (see Peak of Eloquence, sermon 40).

Noun

 * 1)  a twisted saying that is in itself truthful and just, but is used with malicious intentions