"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.  

قَتَلَ رَجُلٌ رَجُلاً عَلَى عَهْدِ رَسُولِ اللَّهِ ﷺ فَجَعَلَ النَّبِيُّ ﷺ دِيَتَهُ اثْنَىْ عَشَرَ أَلْفًا وَذَكَرَ قَوْلَهُ إِلاَّ أَنْ أَغْنَاهُمُ اللَّهُ وَرَسُولُهُ مِنْ فَضْلِهِ فِي أَخْذِهِمُ الدِّيَةَ وَاللَّفْظُ لأَبِي دَاوُدَ  

the Prophet ruled that twelve thousand (should be given) as Diyah. (Hahan)  

أَنَّ النَّبِيَّ ﷺ قَضَى بِاثْنَىْ عَشَرَ أَلْفًا يَعْنِي فِي الدِّيَةِ