Musannaf Ibn Abi Shayba 13:2765

Abu Bakr narrated to us, he said: Ibn ‘Uyaynah narrated to us, from ‘Amr, from Abu Bakr ibn Hafs, he said: ‘Umar wrote to Shurayh that he should judge according to the neighborhood (proximity). He said: So Shurayh used to judge for the man from the people of Kufa against the man from the people of Syria.