Sunan an-Nasa'i 4105
سنن النسائي#4105Sahihأَخْبَرَنَا مُحَمَّدُ بْنُ بَشَّارٍ، قَالَ حَدَّثَنَا عَبْدُ الرَّحْمَنِ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ أَبِي إِسْحَاقَ، قَالَ سَمِعْتُ أَبَا الأَحْوَصِ، عَنْ عَبْدِ اللَّهِ، قَالَ سِبَابُ الْمُسْلِمِ فُسُوقٌ وَقِتَالُهُ كُفْرٌ .
It was narrated that 'Abdullah said:"Defaming a Muslim is evildoing and fighting him is Kufr." (Sahih Mawquf)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih Isnaad Mauquf
Al-AlbaniSahih Isnaad Mauquf
Zubair Ali ZaiIsnaad Sahih
In-book reference: 37:140