Musnad Abu Ya'la al-Mawsili 108:126

Abu Khaythama informed us, Jarir narrated to us, from al-A'mash, from Abu Sufyan, from Jabir, who said: I heard the Messenger of Allah (may Allah bless him and grant him peace) saying: "Harshness and hardness of hearts are toward the East, in Rabi'ah and Mudar, and faith is in the people of the Hijaz."