Muwatta Malik 1579

وَحَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عُمَرَ بْنَ عَبْدِ الْعَزِيزِ، قَضَى أَنَّ دِيَةَ الْيَهُودِيِّ، أَوِ النَّصْرَانِيِّ - إِذَا قُتِلَ أَحَدُهُمَا - مِثْلُ نِصْفِ دِيَةِ الْحُرِّ الْمُسْلِمِ ‏.‏ قَالَ مَالِكٌ الأَمْرُ عِنْدَنَا أَنْ لاَ يُقْتَلَ مُسْلِمٌ بِكَافِرٍ إِلاَّ أَنْ يَقْتُلَهُ مُسْلِمٌ قَتْلَ غِيْلَةٍ فَيُقْتَلُ بِهِ ‏.‏

Yahya related to me from Malik that he heard that Umar ibn Abd al-Aziz gave a decision that when a jew or christian was killed, his blood-money was half the blood-money of a free muslim. Malik said, "What is done in our community, is that a muslim is not killed for a kafir unless the muslim kills him by deceit. Then he is killed for it

Reference

Muwatta Malik 1579

In-book

Book 43, Hadith 28