Jami` at-Tirmidhi Book 49, Hadith 66
that the Messenger of Allah (ﷺ) said to Abu Bakr: "You are my companion at the Hawd, and my companion in the cave."
that the Messenger of Allah (ﷺ) departed one day and entered the Masjid, along with Abu Bakr and 'Umar. One was on his right and the other was on his left, and he was holding their hands, and he said: "This is how we will be resurrected on the Day of Judgement.'"
that the Prophet (ﷺ) saw Abu Bakr and 'Umar and said: "These two are the hearing and the seeing."