Musannaf Ibn Abi Shayba 20:45

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from ‘Umar ibn Rashid, from al-Sha’bi: He said: I heard him saying: The Messenger of Allah (may Allah bless him and grant him peace) judged by [the right of] proximity (al-jiwar).