Sunan Ibn Majah
4184
Sahih+2

It was narrated from Abu Bakrah that the Messenger of Allah (ﷺ) said:“Modesty is part of faith, and faith will be in Paradise. Obscenity in speech is part of harshness and harshness will be in Hell.’”

SahihAl-Albani
SahihMuhammad Fouad Abd al-Baqi