Book 31: The Book Pertaining to the Merits of the Companions (Allah Be Pleased With Them) of the Holy Prophet (May Peace Be Upon Him) (Kitab Al-Fada'il Al-Sahabah)
Chapter 1: The merits of abu bakr siddiq (allah be pleased with him)
Anas b. Malik reported that Abu Bakr Siddiq reported him thus: I saw the feet of the polytheists very close to us as we were in the cave. I said: Allah's Messenger, if one amongst them were to see at his feet he would have surely seen us. Thereupon he said: Abu Bakr, what can befall twain who have Allah as the third One with them.