Musnad Abu Ya'la al-Mawsili 111:2

Hadaba narrated to us, Wahib narrated to us, from Yunus bin Ubayd, from Ammar bin Abi Ammar, who said: I heard Ibn Abbas saying: The Messenger of Allah (may Allah bless him and grant him peace) passed away while he was sixty-five years old. And al-Hasan used to say: The Messenger of Allah (may Allah bless him and grant him peace) passed away while he was sixty years old.