Sunan an-Nasa'i 3994
سنن النسائي#3994SahihIt was narrated that 'Abdullah said:"The first matter concerning which scores will be settled among the people on the Day of Resurrection will be bloodshed
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih Muquf
Al-AlbaniSahih Muquf
Zubair Ali ZaiHasan
In-book reference: 37:29