Musannaf Ibn Abi Shayba 18:736

Abu Bakr narrated to us, he said: Abd al-Rahim ibn Sulayman narrated to us, from Hajjaj, from Rabi’ah ibn Abi Abd al-Rahman ibn al-Daylami, he said: The Messenger of Allah (may Allah bless him and grant him peace) killed a man from the people of the Qibla who had killed a man from the people of the Dhimma (protected non-Muslims). And he said: "I am the most entitled to fulfill the covenant (Dhimma)."