[Machine] In the times of ignorance, when a man from a tribe killed another man, they were not satisfied until they killed a nobleman in retaliation. But if the killer was not noble, they would not kill him and kill someone else instead. They were admonished by the saying of Allah, exalted be He: "And do not kill the soul which Allah has forbidden [to be killed] except by [legal] right. And whoever is killed unjustly - We have given his heir authority, but let him not exceed limits in [the matter of] taking life. Indeed, he has been supported [by the law]." (Quran 17:33) Zaid ibn Aslam said that excess is to kill someone other than the killer. Ash-Shafi'i said that Allah, exalted be He, said: "Prescribed for you is legal retribution for those murdered." (Quran 2:178)  

أَنَّ النَّاسَ فِي الْجَاهِلِيَّةِ إِذَا قَتَلَ الرَّجُلُ مِنَ الْقَوْمِ رَجُلًا لَمْ يَرْضَوْا حَتَّى يَقْتُلُوا بِهِ رَجُلًا شَرِيفًا إِذَا كَانَ قَاتِلُهُمْ غَيْرَ شَرِيفٍ لَمْ يَقْتُلُوا قَاتِلَهُمْ وَقَتَلُوا غَيْرَهُ فَوُعِظُوا فِي ذَلِكَ بِقَوْلِ اللهِ تَبَارَكَ وَتَعَالَى {وَلَا تَقْتُلُوا النَّفْسَ الَّتِي حَرَّمَ اللهُ إِلَّا بِالْحَقِّ وَمَنْ قُتِلَ مَظْلُومًا فَقَدْ جَعَلْنَا لِوَلِيِّهِ سُلْطَانًا فَلَا يُسْرِفْ فِي الْقَتْلِ إِنَّهُ كَانَ مَنْصُورًا} [الإسراء 33] وَقَالَ زَيْدُ بْنُ أَسْلَمَ السَّرَفُ أَنْ يَقْتُلَ غَيْرَ قَاتِلِهِ قَالَ الشَّافِعِيُّ قَالَ اللهُ تَبَارَكَ وَتَعَالَى {كُتِبَ عَلَيْكُمُ الْقِصَاصُ فِي الْقَتْلَى} [البقرة 178] الْآيَةَ