Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
ahmad:20493ʿAbd al-Ṣamad

[Machine] Sa'id Abu 'Uthman narrated to us in Murabba'at al-Ahnaf, and Muslim ibn Abi Bakrah narrated from his father, who heard the Prophet ﷺ saying, "When two Muslims fight each other, the killer and the killed are both in the fire."  

أحمد:٢٠٤٩٣حَدَّثَنَا عَبْدُ الصَّمَدِ

حَدَّثَنَا سَعِيدٌ أَبُو عُثْمَانَ فِي مُرَبَّعَةِ الْأَحْنَفِ حَدَّثَنَا مُسْلِمُ بْنُ أَبِي بَكَرَةَ عَنْ أَبِيهِ سَمِعَ النَّبِيَّ ﷺ يَقُولُ إِذَا اقْتَتَلَ الْمُسْلِمَانِ فَالْقَاتِلُ وَالْمَقْتُولُ فِي النَّارِ