How do we distinguish or balance between "Let him say good or remain silent" and "He who is silent about the truth is a mute devil"? And how do we distinguish between "He who is silent about the truth is a mute devil" and "Whoever among you sees an evil, let him change it," and backbiting and slander, to avoid falling into sin?

A Muslim must speak good, and this includes changing evil according to one's ability: with the hand, and if unable, then with the tongue, and failing that, then with the heart. Speaking good is better than silence, for it is a gain. It is permissible to speak about someone who has committed a sin with the intention of changing the evil or preventing harm. Backbiting is permissible for six reasons: seeking redress, seeking assistance in changing evil, seeking a fatwa (definition), warning Muslims, when the person openly commits sin or innovation, and for identification.