Musannaf Ibn Abi Shayba 27:796

Yahya ibn Adam narrated to us, from Abu al-Ahwas, 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 among the people of the Hijaz, and harshness and hardness of hearts are toward the east, in Rabi'ah and Mudar."