Tribulations
36/4. Chapter:
Verbally abusing a Muslim is Fusuq (disobedience) and fighting Him is Kufr (ungratefulness to Allah)
Sunan Ibn Majah
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا مُحَمَّدُ بْنُ الْحَسَنِ الأَسَدِيُّ، حَدَّثَنَا أَبُو هِلاَلٍ، عَنِ ابْنِ سِيرِينَ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ ـ صلى الله عليه وسلم ـ قَالَ " 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 him is Kufr (ungratefulness to Allah).”
Reference : Sunan Ibn Majah 3940In-book reference : Book 36, Hadith 15English translation : Vol. 5, Book 36, Hadith 3940