Musnad Abu Ya'la al-Mawsili 109:310

Ibn Numayr narrated to us, Ahmad ibn Abdullah narrated to us, from Abu Bakr ibn Ayyash, from al-A’mash, from Abu Sufyan, from Jabir, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Faith is in the people of the Hijaz, and harshness and coarseness are in Rabi'ah and Mudar."