(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).'" (RU)
Reference (RU): Sunan Ibn Majah 3939 (RU)
In-book reference (RU): Book 36, Hadith 14 (RU)
English translation (RU): Vol. 5, Book 36, Hadith 3939 (RU)