Sahih Muslim
The Book Pertaining to the Excellent Qualities of the Holy Prophet (may Peace be upon them) and His Companions (Kitab Al-Fadail)
Book Number: 030 / Hadith Number: 5796
Anas b. Malik reported that Allah's Messenger (may peace be upon him) died when he was sixty-three years old, and so was the case with Abu Bakr, and so was the case with Umar who was also sixty-three (when he died).