Musnad Ahmad 26:875

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Sulayman, he said: I heard 'Umarah ibn 'Umayr narrating from al-Aswad, from 'Abdullah, that he said: "Let not one of you assign a portion to the Shaytan, thinking that it is a duty upon him to turn away from his right side. I have indeed seen the Messenger of Allah, may Allah bless him and grant him peace, turning away from his left side most of the time."