Musnad Ahmad 30:1402

'Affan narrated to us, Hammad—meaning Ibn Salamah—narrated to us, from 'Ali ibn Zayd, he said: Someone who heard Abu Hurayrah narrated to me, saying: The Messenger of Allah (peace and blessings of Allah be upon him) said: "O son of Adam, act as if you see [Allah], and count yourself among the dead. And beware of the supplication of the oppressed."