سُنَنُ النَّسَائِيِّ
Sunan an-Nasa’i 4110
The Book of Fighting [The Prohibition of Bloodshed]
Fighting Muslims
أَخْبَرَنَا مَحْمُودُ بْنُ غَيْلاَنَ، قَالَ حَدَّثَنَا وَكِيعٌ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ زُبَيْدٍ، عَنْ أَبِي وَائِلٍ، عَنْ عَبْدِ اللَّهِ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم سِبَابُ الْمُسْلِمِ فُسُوقٌ وَقِتَالُهُ كُفْرٌ . قُلْتُ لأَبِي وَائِلٍ سَمِعْتَهُ مِنْ عَبْدِ اللَّهِ قَالَ نَعَمْ .
It was narrated from Sufyan bin Zubaid, from Abu Wa'il, from 'Abdullah: "The Messenger of Allah [ﷺ] said: 'Defaming a Muslim is evildoing and fighting him is Kufr.'" I said to Abu Wa'il: "Did you hear it from 'Abdullah?" He said: "Yes."
Sunan an-Nasa'i, 4110Sahih (Darussalam)