Musnad Ahmad 30:1832

Sa'id ibn Mansur and Qutaybah narrated to us, they said: Ya'qub ibn 'Abd al-Rahman narrated to us, from Abu Hazim, from Abu Salih, from Abu Hurayrah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Upon you is hearing and obeying in your hardship and your ease, and in your willingness and your unwillingness, and when others are preferred over you." Qutaybah said: "Obedience," and he did not say: "Hearing."