Ibn Mas'ud (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "A believer is neither one who taunts nor one who curses, nor is he indecent in speech nor abusive." (Tirmidhi, Bayhaqi in Shu'ab al-Iman.) And in another narration of Bayhaqi: "He is neither one who uses obscene language nor one who is abusive." Imam Tirmidhi said: This hadith is gharib. Hasan, narrated by Tirmidhi and Bayhaqi in Shu'ab al-Iman.