Hadith 13:3
‘Abdallah b. Mas'ud reported God’s Messenger as saying, “Shedding of blood will be the first matter about which judgment will be given on the day of resurrection.” (Bukhari and Muslim.)
وَعَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «أَوَّلُ مَا يُقْضَى بَيْنَ النَّاسِ يَوْمَ الْقِيَامَةِ فِي الدِّمَاء»
Original Reference: Mishkat al-Masabih 3448