Musannaf Ibn Abi Shayba 18:888

Abu Bakr narrated to us, he said: Abd al-A’la narrated to us, from Ma’mar, from al-Zuhri, that he said regarding the man who is killed in the Sacred Precinct (al-Haram) or during the Sacred Months: [The blood money is] a blood money and a third of a blood money.