It is narrated from Sadaqah bin Yasar: We sent a message to Sa'id bin al-Musayyib (may Allah have mercy on him) and asked about the blood money (diyah) of a Jew and a Christian. Sa'id (may Allah have mercy on him) replied: "Uthman bin Affan (may Allah be pleased with him) decided that four thousand should be paid in this case."
Hadith Referenceمسند الإمام الشافعي / كتاب القتل والقصاص والديات والقسامة / 1656