(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." (ID)
Reference (ID): Jami` at-Tirmidhi 2634 (ID)
In-book reference (ID): Book 40, Hadith 29 (ID)
English translation (ID): Vol. 5, Book 38, Hadith 2634 (ID)