Mishkat al-Masabih 1 Faith كتاب الإيمان 177

وَعَنْ أَبِي ذَرٍّ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنْ فَارَقَ الْجَمَاعَةَ شبْرًا فقد خلع رقة الْإِسْلَامِ مِنْ عُنُقِهِ» . رَوَاهُ أَحْمَدُ وَأَبُو دَاوُدَ

Abu Dharr reported God’s messenger as saying, “He who separates himself a handbreadth from the community has cast off the rope of Islam from his neck.” Ahmad and Abu Dawud transmitted it.