(15) باب مَا جَاءَ سِبَابُ الْمُسْلِمِ فُسُوقٌ
Narrated Ibn Mas'ud:
that the Messenger of Allah (ﷺ) said: "A Muslim's fighting his brother is disbelief, and verbally abusing him is disobedience." (DE)
Reference (DE): Jami` at-Tirmidhi 2634 (DE)
In-book reference (DE): Book 40, Hadith 29 (DE)
English translation (DE): Vol. 5, Book 38, Hadith 2634 (DE)