(4) باب سِبَابُ الْمُسْلِمِ فُسُوقٌ وَقِتَالُهُ كُفْرٌ
It was narrated from Ibn Mas'ud that the Messenger of Allah (ﷺ)said:
"Verbally abusing a Muslim is Fusuq disobedience and fightinghim is Kufr (ungratefulness to Allah).'" (IT)
Reference (IT): Sunan Ibn Majah 3939 (IT)
In-book reference (IT): Book 36, Hadith 14 (IT)
English translation (IT): Vol. 5, Book 36, Hadith 3939 (IT)