Sahih al-Bukhari 87:20
Narrated Ibn `Abbas:
For the children of Israel the punishment for crime was Al-Qisas only (i.e., the law of equality in punishment) and the payment of Blood money was not permitted as an alternate. But Allah said to this nation (Muslims): 'O you who believe! Qisas is prescribed for you in case of murder, .....(up to) ...end of the Verse. (2.178) Ibn `Abbas added: Remission (forgiveness) in this Verse, means to accept the Blood-money in an intentional murder. Ibn `Abbas added: The Verse: 'Then the relatives should demand Blood-money in a reasonable manner.' (2.178) means that the demand should be reasonable and it is to be compensated with handsome gratitude.
Reference
Sahih al-Bukhari 87:20
In-book reference
Book 87, Hadith 20
Arabic Text
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا سُفْيَانُ، عَنْ عَمْرٍو، عَنْ مُجَاهِدٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ كَانَتْ فِي بَنِي إِسْرَائِيلَ قِصَاصٌ، وَلَمْ تَكُنْ فِيهِمُ الدِّيَةُ فَقَالَ اللَّهُ لِهَذِهِ الأُمَّةِ {كُتِبَ عَلَيْكُمُ الْقِصَاصُ فِي الْقَتْلَى} إِلَى هَذِهِ الآيَةِ {فَمَنْ عُفِيَ لَهُ مِنْ أَخِيهِ شَىْءٌ}. قَالَ ابْنُ عَبَّاسٍ فَالْعَفْوُ أَنْ يَقْبَلَ الدِّيَةَ فِي الْعَمْدِ، قَالَ {فَاتِّبَاعٌ بِالْمَعْرُوفِ} أَنْ يَطْلُبَ بِمَعْرُوفٍ وَيُؤَدِّيَ بِإِحْسَانٍ.