سُنَنُ النَّسَائِيِّ
Sunan an-Nasa’i 3995
The Book of Fighting [The Prohibition of Bloodshed]
The Gravity of the Sin of Shedding Blood
أَخْبَرَنَا أَحْمَدُ بْنُ حَرْبٍ، قَالَ حَدَّثَنَا أَبُو مُعَاوِيَةَ، عَنِ الأَعْمَشِ، عَنْ أَبِي وَائِلٍ، عَنْ عَمْرِو بْنِ شُرَحْبِيلَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم أَوَّلُ مَا يُقْضَى فِيهِ بَيْنَ النَّاسِ يَوْمَ الْقِيَامَةِ فِي الدِّمَاءِ .
It was narrated that 'Amr bin Shurahbil said: "The Messenger of Allah [ﷺ] said: 'The first matter concerning which scores will be settled among the people on the Day of Resurrection will be bloodshed.'"
Sunan an-Nasa'i, 3995Sahih (Darussalam)