Musnad Ahmad 26:84

Abu Mu'awiyah and Ibn Numayr narrated to us, from al-A'mash, and Yahya, from al-A'mash, 'Umarah narrated to me, al-Aswad narrated to me—the meaning is from 'Umarah, from al-Aswad, from 'Abdullah: "Let not one of you assign a portion of himself to Satan, thinking that it is a duty upon him not to turn away except from his right side. I have indeed seen the Messenger of Allah, may Allah bless him and grant him peace, and most of his turning away was from his left side."