Sahih Muslim 1371bBook 15, Hadith 535
وَحَدَّثَنَا أَبُو بَكْرِ بْنُ النَّضْرِ بْنِ أَبِي النَّضْرِ، حَدَّثَنِي أَبُو النَّضْرِ، حَدَّثَنِي عُبَيْدُ اللَّهِ، الأَشْجَعِيُّ عَنْ سُفْيَانَ، عَنِ الأَعْمَشِ، بِهَذَا الإِسْنَادِ . مِثْلَهُ وَلَمْ يَقُلْ " يَوْمَ الْقِيَامَةِ " وَزَادَ " وَذِمَّةُ الْمُسْلِمِينَ وَاحِدَةٌ يَسْعَى بِهَا أَدْنَاهُمْ فَمَنْ أَخْفَرَ مُسْلِمًا فَعَلَيْهِ لَعْنَةُ اللَّهِ وَالْمَلاَئِكَةِ وَالنَّاسِ أَجْمَعِينَ لاَ يُقْبَلُ مِنْهُ يَوْمَ الْقِيَامَةِ عَدْلٌ وَلاَ صَرْفٌ " .
" The protection granted by Muslims is one and must be respected by the humblest of them. And he who broke the covenant made by a Muslim, there is a curse of Allah, of his angels, and of the whole people upon him, and neither an obligatory act nor a supererogatory act would be accepted from him as recompense on the Day of Resurrection."