Sunan Ibn Majah 2659
سنن ابن ماجه#2659Sahihحَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، حَدَّثَنَا حَاتِمُ بْنُ إِسْمَاعِيلَ، حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ عَيَّاشٍ، عَنْ عَمْرِو بْنِ شُعَيْبٍ، عَنْ أَبِيهِ، عَنْ جَدِّهِ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لاَ يُقْتَلُ مُسْلِمٌ بِكَافِرٍ " .
It was narrated from 'Amr bin Shu'aib, from his father, from his grandfather, that the Messenger of Allah (ﷺ) said:“A Muslim should not be killed in retaliation for the murder of a disbeliever.”
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Al-AlbaniHasan Sahih
Muhammad Fouad Abd al-BaqiHasan Sahih
Shuaib Al ArnautSahih Lighairihi
Zubair Ali ZaiSahih
In-book reference: 21:45