Musannaf Ibn Abi Shayba 33:1472

Muhammad ibn Abdullah ibn al-Zubayr narrated to us, from Ibn Abi Rawwad, who said: Abu Sa’id narrated to me, from Zayd ibn Arqam, who said: Worship Allah as if you see Him, for if you do not see Him, He surely sees you. And count yourself among the dead. And fear the supplication of the oppressed, for it is answered.