Volume 8 · Book 73 · Hadith 58
Narrated Anas bin Malik: The Prophet was not one who would abuse (others) or say obscene words, or curse (others), and if he wanted to admonish anyone of us, he used to say: "What is wrong with him, his forehead be dusted!"
— Sahih Bukhari, Volume 8, Book 73: Good Manners and Form (Al-Adab), Hadith #58