Musnad Ahmad 941:48

Ahmad ibn al-Hajjaj narrated to us, Ibn Abi Fudayk narrated to us, from Ibn Abi Dhi’b, from Shu’bah, from Ibn Abbas, from Usamah ibn Zayd: "The Messenger of Allah, peace and blessings of Allah be upon him, had him ride behind him on the day of Arafah until he entered the mountain pass. Then he poured water and performed ablution, then he mounted and did not pray."