Musnad Ahmad 952:4

Qutaybah ibn Sa'id narrated to us, Layth ibn Sa'd narrated to us, from Khalid ibn Yazid, from Sa'id ibn Abi Hilal, from Yazid ibn 'Abd Allah, from 'Umayr, the freed slave of Abi al-Lahm, from Abi al-Lahm: That he saw the Messenger of Allah, may Allah bless him and grant him peace, at the stones of al-Zayt, seeking rain, while he was raising his hands, supplicating.