Sunan an-Nasa'i, Volume 5, Book 37, Hadith 3996 (DarusSalam) ⓘ
It was narrated that 'Abdullah said: "The Messenger of Allah [SAW] said: 'The first thing concerning which a person will be brought to account will be the Salah, and the first thing concerning which scores will be settled among the people, will be bloodshed."
أَخْبَرَنَا سَرِيعُ بْنُ عَبْدِ اللَّهِ الْوَاسِطِيُّ الْخَصِيُّ، قَالَ حَدَّثَنَا إِسْحَاقُ بْنُ يُوسُفَ الأَزْرَقُ، عَنْ شَرِيكٍ، عَنْ عَاصِمٍ، عَنْ أَبِي وَائِلٍ، عَنْ عَبْدِ اللَّهِ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " أَوَّلُ مَا يُحَاسَبُ بِهِ الْعَبْدُ الصَّلاَةُ وَأَوَّلُ مَا يُقْضَى بَيْنَ النَّاسِ فِي الدِّمَاءِ " .
also referenced under: Hadith 3991 (Reference) & Book 37, Hadith 26 (In-Book)