It is narrated from Sayyiduna Mu'awiyah bin Abi Sufyan (may Allah be pleased with him) that he said: I heard from the Messenger of Allah (peace and blessings be upon him) words by which Allah benefited me. I heard him (peace and blessings be upon him) say: "Turn away from (the faults of) people. Do you not see that if you pursue suspicion about people, you will corrupt them or come close to corrupting them?"
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 16908