Sunan an-Nasa'i 3993
سنن النسائي#3993Sahihأَخْبَرَنَا أَحْمَدُ بْنُ سُلَيْمَانَ، قَالَ حَدَّثَنَا أَبُو دَاوُدَ، عَنْ سُفْيَانَ، عَنِ الأَعْمَشِ، عَنْ أَبِي وَائِلٍ، قَالَ قَالَ عَبْدُ اللَّهِ أَوَّلُ مَا يُقْضَى بَيْنَ النَّاسِ يَوْمَ الْقِيَامَةِ فِي الدِّمَاءِ .
It was narrated from 'Abdullah that:The Messenger of Allah [SAW] said: "The first matter concerning which scores will be settled among the people on the Day of Resurrection will be bloodshed
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 Muquf
Al-AlbaniSahih Muquf
Zubair Ali ZaiHasan
In-book reference: 37:28