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