Musnad Ahmad 27:395

Muhammad ibn Ubayd narrated to us, Ubayd Allah narrated to us, from Nafi, from Ibn Umar: "That the Messenger of Allah (peace and blessings of Allah be upon him) used to exit by way of al-Shajarah. And he used to enter Makkah from the upper mountain pass (al-Thaniyah al-Ulya), and exit from the lower mountain pass (al-Thaniyah al-Sufla)."