Merits of the Helpers in Madinah (Ansaar)
Bukhari :: Book 5 :: Volume 58 :: Hadith 259
Narrated Abu Bakr:
I was with the Prophet in the Cave. When I raised my head, I saw the feet of the people. I said, "O Allah's Apostle! If some of them should look down, they will see us." The Prophet said, "O Abu Bakr, be quiet! (For we are) two and Allah is the Third of us."