(4) باب سِبَابُ الْمُسْلِمِ فُسُوقٌ وَقِتَالُهُ كُفْرٌ
It was narrated from Abu Hurairah that the Prophet (ﷺ) said:
"Verbally abusing a Muslim is Fusuq (disobedience) and fighting himisKufr (ungratefulness to Allah)." (DE)
Reference (DE): Sunan Ibn Majah 3940 (DE)
In-book reference (DE): Book 36, Hadith 15 (DE)
English translation (DE): Vol. 5, Book 36, Hadith 3940 (DE)