Yahya bin Bukayr said: Abu Bakr (may Allah be pleased with him) was made caliph on the same day that the Messenger of Allah (peace and blessings be upon him) passed away. He passed away in Jumada al-Akhirah in the year 13 AH, and his age at the time of his death, as Sayyidah Aishah (may Allah be pleased with her) stated, was the same as the age of the Messenger of Allah (peace and blessings be upon him), that is, sixty-three years.
Hadith Referenceالمعجم الكبير للطبراني / العشرة / 42