Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrated: "At the time of the death of the Messenger of Allah (peace and blessings be upon him), he (peace and blessings be upon him) was sixty-five years old."
And al-Hasan (al-Basri) (may Allah have mercy on him) used to say: "He (peace and blessings be upon him) passed away at the age of sixty."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12788