Sunan an-Nasa'i 3989
سنن النسائي#3989Hasanأَخْبَرَنَا عَمْرُو بْنُ هِشَامٍ، قَالَ حَدَّثَنَا مَخْلَدُ بْنُ يَزِيدَ، عَنْ سُفْيَانَ، عَنْ مَنْصُورٍ، عَنْ يَعْلَى بْنِ عَطَاءٍ، عَنْ أَبِيهِ، عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو، قَالَ قَتْلُ الْمُؤْمِنِ أَعْظَمُ عِنْدَ اللَّهِ مِنْ زَوَالِ الدُّنْيَا .
It was narrated that 'Abdullah bin 'Amr said:"Killing a believer is more grievous before Allah than the extinction of the whole world
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 Ghuddah-
Zubair Ali ZaiHasan
In-book reference: 37:24