Musannaf Ibn Abi Shayba 26:96

Waki’ narrated to us, he said: Sufyan narrated to us, from ‘Abd al-Rahman ibn al-Harith ibn ‘Ayyash ibn Abi Rabi’ah al-Zuraqi, from Hakim ibn Hakim ibn ‘Abbad ibn Hunayf al-Ansari, from Abu Umamah ibn Sahl ibn Hunayf, that a man shot a man with an arrow and killed him, and he had no heir except a maternal uncle. Abu ‘Ubaydah ibn al-Jarrah wrote to ‘Umar regarding that. ‘Umar wrote back to him that the Messenger of Allah (may Allah bless him and grant him peace) said: "Allah and His Messenger are the guardian of the one who has no guardian, and the maternal uncle is the heir of the one who has no heir."