Musnad Ahmad 32:523

Yunus and Surayj narrated to us, they said: Fulayh narrated to us, from Hilal ibn Ali, who said: Anas ibn Malik said: The Messenger of Allah (peace and blessings of Allah be upon him) was not one who insulted, nor was he foul-mouthed, nor was he a curser. And he would say to one of us when rebuking him: "What is the matter with him? May his forehead be rubbed with dust."