Musannaf Ibn Abi Shayba 18:1301

Abu Bakr narrated to us, he said: Ibn Mubarak narrated to us, from Ma'mar, that a man from the people of India arrived under a guarantee of safety, and a man from the Muslims killed him in retaliation for his brother. So he wrote regarding that to Umar ibn Abd al-Aziz. He wrote back: "Do not kill him, but take the blood money from him and send it to his heirs." And he ordered that he be imprisoned.