Musnad Ahmad 26:480

Ibn Fudayl narrated to us, Harun ibn Antarah narrated to us, from Abd al-Rahman ibn al-Aswad, who said: Alqamah and al-Aswad sought permission to enter upon Abdullah. He said: "There will soon be rulers over you who will be preoccupied away from the time of prayer, so pray it at its time." Then he stood and prayed between me and him, then he said: "Thus I saw the Messenger of Allah, may Allah bless him and grant him peace, do."