Sahih Bukhari
Good Manners and Form (Al-Adab)
Volume: 008 / Book Number: 073 / Hadith Number: 72
Narrated Anas:
Allah's Apostle was neither a Fahish (one who had a bad tongue) nor a Sabbaba (one who abuses others) and he used to say while admonishing somebody, "What is wrong with him? May dust be on his forehead!"