Musnad Abu Ya'la al-Mawsili 155:5

Abdullah ibn Muhammad ibn Asma’ narrated to us, Abdullah ibn al-Mubarak narrated to us, from Ma’mar, from al-Zuhri, who said: Sa’id ibn al-Musayyib narrated to me that Abu Hurayrah said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "Indeed, the likeness of the mujahid in the way of Allah—and Allah knows best who struggles in His way—is like the likeness of the fasting, devout, humble, bowing, and prostrating one."