وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، أَنَّ مَرْوَانَ بْنَ الْحَكَمِ، كَتَبَ إِلَى مُعَاوِيَةَ بْنِ أَبِي سُفْيَانَ أَنَّهُ أُتِيَ بِمَجْنُونٍ قَتَلَ رَجُلاً ‏.‏ فَكَتَبَ إِلَيْهِ مُعَاوِيَةُ أَنِ اعْقِلْهُ وَلاَ تُقِدْ مِنْهُ فَإِنَّهُ لَيْسَ عَلَى مَجْنُونٍ قَوَدٌ ‏.‏ قَالَ مَالِكٌ فِي الْكَبِيرِ وَالصَّغِيرِ إِذَا قَتَلاَ رَجُلاً جَمِيعًا عَمْدًا أَنَّ عَلَى الْكَبِيرِ أَنْ يُقْتَلَ وَعَلَى الصَّغِيرِ نِصْفُ الدِّيَةِ ‏.‏ قَالَ مَالِكٌ وَكَذَلِكَ الْحُرُّ وَالْعَبْدُ يَقْتُلاَنِ الْعَبْدَ فَيُقْتَلُ الْعَبْدُ وَيَكُونُ عَلَى الْحُرِّ نِصْفُ قِيمَتِهِ ‏.‏

Yahya related to me from Malik from Yahya ibn Said that Marwanibn al-Hakam wrote to Muawiya ibn Abi Sufyan that a madman was broughtto him who had killed a man. Muawiya wrote to him, "Tie him up and donot inflict any retaliation on him. There is no retaliation against amadman." Malik said about an adult and a child when theymurder a man together, "The adult is killed and the child pays halfthe full blood-money." Malik said, "It is like that with afreeman and a slave when they murder a slave. The slave is killed andthe freeman pays half of his value." Translation Not Available

Book Ref: Muwatta Imam Malik Book 43 Hadith 1558
Web Ref:  Muwatta Imam Malik Book 43 Hadith 3