The Forty Hadith of Imam Nawawi — No harm and no reciprocation of harm

There should be neither harming (darar) nor reciprocating harm (dirar).

I heard the Messenger of Allah (ﷺ) say, “Whosoever of you sees an evil, let him change it with his hand; and if he is not able to do so, then [let him change it] with his tongue; and if he is not able to do so, then with his heart — and that is the weakest of faith.”