Al-Baqarah - 2:178

يَا أَيُّهَا الَّذِينَ آمَنُواْ كُتِبَ عَلَيْكُمُ الْقِصَاصُ فِي الْقَتْلَى الْحُرُّ بِالْحُرِّ وَالْعَبْدُ بِالْعَبْدِ وَالأُنثَى بِالأُنثَى فَمَنْ عُفِيَ لَهُ مِنْ أَخِيهِ شَيْءٌ فَاتِّبَاعٌ بِالْمَعْرُوفِ وَأَدَاء إِلَيْهِ بِإِحْسَانٍ ذَلِكَ تَخْفِيفٌ مِّن رَّبِّكُمْ وَرَحْمَةٌ فَمَنِ اعْتَدَى بَعْدَ ذَلِكَ فَلَهُ عَذَابٌ أَلِيمٌ
[2:178]
O you who believe! retaliation is prescribed for you in the matter of the slain, the free for the free, and the slave for the slave, and the female for the female, but if any remission is made to any one by his (aggrieved) brother, then prosecution (for the bloodwit) should be made according to usage, and payment should be made to him in a good manner; this is an alleviation from your Lord and a mercy; so whoever exceeds the limit after this he shall have a painful chastisement.
O ye who believe! the law of equality is prescribed to you in cases of murder: the free for the free, the slave for the slave, the woman for the woman. But if any remission is made by the brother of the slain, then grant any reasonable demand, and compensate him with handsome gratitude, this is a concession and a Mercy from your Lord. After this whoever exceeds the limits shall be in grave penalty.
O ye who believe! Retaliation is prescribed for you in the matter of the murdered; the freeman for the freeman, and the slave for the slave, and the female for the female. And for him who is forgiven somewhat by his (injured) brother, prosecution according to usage and payment unto him in kindness. This is an alleviation and a mercy from your Lord. He who transgresseth after this will have a painful doom.