The first (thing) that will be decided among people on the Day of Judgment will pertain to bloodshed.  

قَالَ رَسُولُ اللَّهِ ﷺ أَوَّلُ مَا يُقْضَى بَيْنَ النَّاسِ يَوْمَ الْقِيَامَةِ فِي الدِّمَاءِ  

This hadith has been narrated on the authority of 'Abdullah through another chain of transmitters with a slight variation of words.  

عَنِ النَّبِيِّ ﷺ بِمِثْلِهِ غَيْرَ أَنَّ بَعْضَهُمْ قَالَ عَنْ شُعْبَةَ يُقْضَى وَبَعْضُهُمْ قَالَ يُحْكَمُ بَيْنَ النَّاسِ