Abu Dawud
General Behavior
Book Number: 036 / Hadith Number: 4870
Narated By Mu'awiyah : I heard the Apostle of Allah (pbuh) say: If you search for the faults of the people, you will corrupt them, or will nearly corrupt them. AbudDarda' said: These are the words which Mu'awiyah himself from the Apostle of Allah (pbuh), and Allah benefited him by them.