Musnad Ahmad 27:1463

Ishaq ibn Isa narrated to us, Malik informed us, from Nafi, from Ibn Umar, "That the Messenger of Allah (peace and blessings of Allah be upon him) made his camel kneel at the Al-Batha which is at Dhu al-Hulayfah, and he prayed there." And Ibn Umar used to do that.