Sunan an-Nasa'i 4063
سنن النسائي#4063Sahihأَخْبَرَنَا مُوسَى بْنُ عَبْدِ الرَّحْمَنِ، قَالَ حَدَّثَنَا مُحَمَّدُ بْنُ بِشْرٍ، قَالَ حَدَّثَنَا سَعِيدٌ، عَنْ قَتَادَةَ، عَنِ الْحَسَنِ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَنْ بَدَّلَ دِينَهُ فَاقْتُلُوهُ " . قَالَ أَبُو عَبْدِ الرَّحْمَنِ وَهَذَا أَوْلَى بِالصَّوَابِ مِنْ حَدِيثِ عَبَّادٍ .
It was narrated that Al-Hasan said:"The Messenger of Allah [SAW] said: 'Whoever changes his religion, kill him
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:
Abu GhuddahSahih Lighairihi
Al-AlbaniSahih
Zubair Ali ZaiHasan
In-book reference: 37:98