Sunan an-Nasa'i, Volume 5, Book 45, Hadith 4807 (DarusSalam) ⓘ
It was narrated that Ibn 'Abbas said: "A man killed another man during the time of the Messenger of Allah, and the Prophet set the Diyah at twelve thousand. And he mentioned His saying: And they could not find any cause to do so except that Allah and His Messenger had enriched them of His Bounty. concerning them taking the Dyah." (Hasan) This is the wording of Abu Dawud.
أَخْبَرَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، عَنْ مُعَاذِ بْنِ هَانِئٍ، قَالَ حَدَّثَنِي مُحَمَّدُ بْنُ مُسْلِمٍ، قَالَ حَدَّثَنَا عَمْرُو بْنُ دِينَارٍ، ح وَأَخْبَرَنَا أَبُو دَاوُدَ، قَالَ حَدَّثَنَا مُعَاذُ بْنُ هَانِئٍ، قَالَ حَدَّثَنَا مُحَمَّدُ بْنُ مُسْلِمٍ، عَنْ عَمْرِو بْنِ دِينَارٍ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَتَلَ رَجُلٌ رَجُلاً عَلَى عَهْدِ رَسُولِ اللَّهِ صلى الله عليه وسلم فَجَعَلَ النَّبِيُّ صلى الله عليه وسلم دِيَتَهُ اثْنَىْ عَشَرَ أَلْفًا وَذَكَرَ قَوْلَهُ إِلاَّ أَنْ أَغْنَاهُمُ اللَّهُ وَرَسُولُهُ مِنْ فَضْلِهِ فِي أَخْذِهِمُ الدِّيَةَ . وَاللَّفْظُ لأَبِي دَاوُدَ .
also referenced under: Hadith 4803 (Reference) & Book 45, Hadith 98 (In-Book)