It was narrated that Mujahid said:"Al-Qisas (the Law of Equality in punishment) is prescribed for you in case of murder: the free for the free[2] The rule for the Children of Israel was Qisas, and not Diyah. Then Allah, the Mighty and Sublime, revealed the Diyah to them, and He revealed this ruling to this Ummah as an alleviation of the ruling that applied to the Children of Israel."
أَخْبَرَنَا مُحَمَّدُ بْنُ إِسْمَاعِيلَ بْنِ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا عَلِيُّ بْنُ حَفْصٍ، قَالَ حَدَّثَنَا وَرْقَاءُ، عَنْ عَمْرٍو، عَنْ مُجَاهِدٍ، قَالَ { كُتِبَ عَلَيْكُمُ الْقِصَاصُ فِي الْقَتْلَى الْحُرُّ بِالْحُرِّ } قَالَ كَانَ بَنُو إِسْرَائِيلَ عَلَيْهِمُ الْقِصَاصُ وَلَيْسَ عَلَيْهِمُ الدِّيَةَ فَأَنْزَلَ اللَّهُ عَزَّ وَجَلَّ عَلَيْهِمُ الدِّيَةَ فَجَعَلَهَا عَلَى هَذِهِ الأُمَّةِ تَخْفِيفًا عَلَى مَا كَانَ عَلَى بَنِي إِسْرَائِيلَ .
Nesai
The Book of Oaths (qasamah), Retaliation and Blood Money • Hadith 4782