Musannaf Ibn Abi Shayba 37:639

Al-Fadl ibn Dukayn narrated to us, he said: Ubayd ibn Tufayl Abu Saydan al-Ghatafani narrated to us, he said: Rib'i ibn Hirash narrated to me, from Umar ibn al-Khattab, he said: Leave these broad-faced ones alone as long as they leave you alone. For by Allah, I wish there were a sea between us and them that could not be crossed.