Sahih Muslim
Sahih Muslim Book 031, Hadith Number 5871.
Hadith Section/Book: Sahih Muslim Sahih Muslim Book 31. The Merits Of The Companions (PBUT) Of The Holy Prophet (PBUH)
Chapter : The merits of Abu Bakr Siddiq (Allah be pleased with him).
'Abdullah b. Mas'ud reported Allah's Messenger (may peace be upon him) 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 Glorious, has taken your brother and companion (meaning Prophet himself) as a friend.
'Abdullah b. Mas'ud reported Allah's Messenger (may peace be upon him) 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 Glorious, has taken your brother and companion (meaning Prophet himself) as a friend.