大唐西域記 8.41

8.41

如來以印度吠舍佉月後半八日成等正覺，當此三月八日也。上座部則吠舍佉月後半十五日成等正覺，當此三月十五日也。是時如來年三十矣。或曰年三十五矣。

The figure still exists in its perfect state as it was made by the sacred art of the god. It stands in a dark chamber ; lamps and torches are kept burning therein ; but those who wish to see the sacred features cannot do so by coming into the chamber; they should in the morning reflect the sunlight by means of a great mirror on the interior of the room ; the sacred marks may then be seen. Those who behold them find their religious emotions much increased. Tathāgata obtained complete enlightenment (Samyak sambodhi) on the eighth day of the latter half of the Indian month Vaiśākha (Fei-she-kie), which is with us the eighth day of the third month. But the Sthavira school (Shang-tso-pu) say on the fifteenth day of the second half of Vaiśākha, which corresponds with us to the fifteenth day of the third month. Tathāgata was then thirty years old, or, according to others, thirty-five years.