Sahih Bukhari Volume 008, Book 074, Hadith Number 313.

Narated By Abu Huraira : Allah's Apostle said "The Prophet) Abraham circumcised himself after he had passed the age of eighty years and he circumcised himself with an adze."

Narrated Said bin Jubair: Ibn 'Abbas was asked, "How old were you when the Prophet died?" He replied. "At that time I had been circumcised." At that time, people did not circumcise the boys till they attained the age of puberty. Sa'id bin Jubair said, "Ibn 'Abbas said, 'When the Prophet died, I had already been circumcised."