Musnad Ahmad 28:221

Yazid narrated to us, Hajjaj informed us, from ‘Ata’, from Jabir; and from Abu al-Zubayr, from Jabir; and from ‘Amr ibn Shu‘ayb, from his father, from his grandfather, who said: "The Messenger of Allah, may Allah bless him and grant him peace, appointed Dhu al-Hulayfah for the people of Medina, al-Juhfah for the people of Syria, Yalamlam for the people of Yemen and the people of Tihamah, Qarn for the people of Ta'if—which is Najd—and Dhat ‘Irq for the people of Iraq."