法苑珠林 32.10

32.10

Furthermore, the Chuchu jing states: "When the Buddha smiled at that time, five-coloured light issued from his mouth for five reasons: first, because he wished to prompt someone to ask a question, and the question would be beneficial; second, for fear that people might say the Buddha does not know how to smile; third, in order to display the light within his mouth; fourth, to smile at those who lack sincere earnestness; fifth, to smile at the arhats who cling to emptiness and do not attain the bodhisattva path. That the light returned and entered through the crown of his head was to display great illumination to people of the future."