The Messenger of Allah ﷺ said, "Among the people most generous to me with his companionship and his wealth is Abu Bakr. If I were to take a close friend from my community, I would have taken Abu Bakr, but the bond of Islam is enough. Let no door remain open into the mosque except the door of Abu Bakr."
أن رسول الله ﷺ قال: إن من أمن الناس علي في صحبته وماله أبا بكر، ولو كنت متخذا خليلا من أمتي لاتخذت أبا بكر إلا خلة الإسلام، لا يبقين في المسجد خوخة إلا خوخة أبي بكر.
Malik narrated it in Muwatta (944, the narration of Muhammad bin Hasan Shaybani) from Abu Nadr, the freed slave of Umar bin Ubaydullah, from Ubayd bin Hunayn, from Abu Saeed Khudri, who related it.Bukhari narrated it in the Virtues of the Ansar (3904), and Muslim in the Virtues of the Companions (2382-2), both of them through the route of Malik, with the same wording.