Sahih Bukhari
Merits of the Helpers in Madinah (Ansaar)
Volume: 005 / Book Number: 058 / Hadith Number: 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."