It is narrated from Sadaqah bin Yasar, may Allah have mercy on him, who said: We sent a message to Sa'id bin al-Musayyib, may Allah have mercy on him, asking him about the blood money (diyah) of a contractee (dhimmi). He replied that Uthman bin Affan, may Allah be pleased with him, had decided it to be four thousand (dirhams). Sadaqah says: We asked, "Who killed him?" He said, then he threw pebbles at us. Imam Shafi'i, may Allah have mercy on him, said: These were the people who asked him this question at the end.
Hadith Referenceمسند الإمام الشافعي / كتاب القتل والقصاص والديات والقسامة / 1655
Hadith Takhrijاسناده صحیح اخرجه البيهقى 8 / 100 - وفى المعرفة السنن والآثار له (4930) وابن ابي شيبة (27455)۔