Bismillah Walhamdulillah Was Salaatu Was Salaam ‘ala Rasulillah
Narrated by Abu Dhar (Radi-Allahu ‘anhu):
That he heard the Prophet (Sallallahu ‘Alaihi Wa Sallam) saying, “If somebody accuses another of Fusuq (by calling him ‘Fasiq’ i.e. a wicked person) or accuses him of Kufr, such an accusation will revert to him (i.e. the accuser) if his companion (the accused) is innocent.”
Bukhari Vol. 8 : No. 71