It was narrated from 'Ikrimah, from Ibn 'Abbas, that :

the Prophet (ﷺ) set the blood money at twelve thousand (Dirham). He said: “This is what Allah says: 'And they could not find any cause to do so except that Allah and his Messenger (ﷺ) had enriched them of His bounty.'” He said: “By their taking the blood money.”

حَدَّثَنَا الْعَبَّاسُ بْنُ جَعْفَرٍ، حَدَّثَنَا مُحَمَّدُ بْنُ سِنَانٍ، حَدَّثَنَا مُحَمَّدُ بْنُ مُسْلِمٍ، عَنْ عَمْرِو بْنِ دِينَارٍ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم جَعَلَ الدِّيَةَ اثْنَىْ عَشَرَ أَلْفًا قَالَ ذَلِكَ قَوْلُهُ ‏{وَمَا نَقَمُوا إِلاَّ أَنْ أَغْنَاهُمُ اللَّهُ وَرَسُولُهُ مِنْ فَضْلِهِ}‏ قَالَ بِأَخْذِهِمُ الدِّيَةَ ‏.‏