(9) CHAPTER. The Statement of Allah: “...The second of two, when they (Muhammad and Abu bakr ) were in the cave, and he said to his companion (Abu bakr ) 'Be not sad (or afraid), surely Allah is with us.' ” (V.9:40)
Narrated Abu Bakr: I was in the company of the Prophet in the cave, and on seeing the traces of the pagans, I said, O Allah's Messenger If one of them (pagans) should lift up his foot, he will see us. He said, What do you think of two, the third of whom is Allah?