Sunan an-Nasa'i 3992
سنن النسائي#3992Sahihأَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ الأَعْلَى، عَنْ خَالِدٍ، حَدَّثَنَا شُعْبَةُ، عَنْ سُلَيْمَانَ، قَالَ سَمِعْتُ أَبَا وَائِلٍ، يُحَدِّثُ عَنْ عَبْدِ اللَّهِ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " أَوَّلُ مَا يُحْكَمُ بَيْنَ النَّاسِ فِي الدِّمَاءِ " .
It was narrated that 'Abdullah said:"The Messenger of Allah [SAW] said: 'The first matter concerning which judgment will be passed among the people 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
Al-AlbaniSahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 37:27