Avoid spying, suspicion, slandering and backbiting

 "O you who believe! Avoid much suspicion, in deeds some suspicions are sins. And spy not neither backbite one another. Would one of you like to eat the flesh of his dead brother? You would hate it (so hate backbiting). And fear Allah, verily, Allah is the One who accepts repentance, Most Merciful" (Quran 49: 12)