أَخْبَرَنَا 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." Translation Not Available

Book Ref: Sunan An Nisai Book 37 Hadith 3993
Web Ref:  Sunan An Nisai Vol 5 Book 37 Hadith 3998