Mishkat al-Masabih
Mishkat al-Masabih 3548
Killing Apostates and People who Strive to cause Mischief - Section 2
Arabic hadith text
وَعَنْ أَبِي هُرَيْرَةَ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «الْإِيمَانُ قَيَّدَ الْفَتْكَ لَا يفتِكُ مُؤمنٌ» . رَوَاهُ أَبُو دَاوُد
Translation
Abu Huraira reported the Prophet as saying, “Faith is an assurance of safety from being killed unawares. A believer does not kill another unawares.” Abu Dawud transmitted it.