The Messenger of Allah ﷺ said, "Modesty is part of faith, and faith leads to Paradise. Obscenity is part of harshness, and harshness leads to the Fire."
قال رسول الله ﷺ: الحياء من الإيمان والإيمان في الجنة، والبذاء من الجفاء، والجفاء في النار.
Reported by Ibn Majah (4184), Bukhari in Adab al-Mufrad (1314), Ibn Hibban (5704), and Hakim (1/52), all of them from the hadith of Hushaym, from Mansur, from Hasan, from Abu Bakra, who narrated it.Its chain of transmission is sahih. There is disagreement about whether Hasan heard directly from Abu Bakra. Bukhari held that he did hear from him, while others denied it. Hasan is a mudallis and he did narrate this using ambiguous transmission language (an'ana), but Ibn Hibban stated explicitly in his introduction that when a mudallis states his source clearly elsewhere, "I do not mind mentioning him even when he uses ambiguous transmission language," meaning that he simply abbreviates the form of transmission. I have judged this hadith to be sahih because it does not concern matters of legal rulings.His saying "crude speech" (al-bidha) means foul, obscene talk.