(1) باب مِنْ فَضَائِلِ أَبِي بَكْرٍ الصِّدِّيقِ رضى الله عنه
'Abdullah b. Mas'ud reported Allah's Messenger (ﷺ) as saying:
If I were to choose a bosom friend I would have definitely chosen Abu Bakr as my bosom friend, but he is my brother and my companion and Allah, the Exalted and Gliorious. has taken your brother and companion (meaning Prophet himself) as a friend.
Reference: Sahih Muslim 2383 a
In-book reference: Book 44, Hadith 4
USC-MSA web (English) reference(deprecated numbering scheme): Book 31, Hadith 5871