Hadithcore
Mishkat al-Masabih, 3548

Abu Huraira reported the Prophet (ﷺ) as saying, “Faith is an assurance of safety from being killed unawares. A believer does not kill another unawares.” Abu Dawud transmitted it.

وَعَنْ أَبِي هُرَيْرَةَ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «الْإِيمَانُ قَيَّدَ الْفَتْكَ لَا يفتِكُ مُؤمنٌ» . رَوَاهُ أَبُو دَاوُد

References1 variant
In-Book Reference
Book 16, Hadith 94