Abu Bakr As-Siddique was the closest of the Companions in relationship to the Prophet (sas). From Sahih Al-Bukhari: Ibn Abbas reports: "The Prophet (sas) came out during his illness from which he died his head bound with a cloth. He sat on the minbar, thanked Allah, praised Him and said: "There is no one among the people who has been more generous to me with his life and his property than Abu Bakr ibn Abi Quhaafa and if I was to take a bosom friend, I would take Abu Bakr as my bosom friend. But, the friendship of Islam is better. Block off every door in this Masjid except the door of Abu Bakr.