Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates that the Prophet (peace and blessings be upon him) said: "The blood money of a dhimmi is half the blood money of a Muslim."
Al-Tabarani recorded it in al-Mu'jam al-Awsat. Its chain contains a group of narrators whom I do not know.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الديات / 10783