Musannaf Ibn Abi Shayba 13:2937

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Mis’ar narrated to us, from Azhar al-Attar, from Muharib ibn Dithar, he said: Umar said: "Send back the disputing parties until they reconcile, for the finality of judgment breeds grudges between people."