梵網經述記卷第一 1.30

1.30

經。即口放無量光明　釋曰。第三放光。欲說戒光明故。所以口放光也。有四因緣。是故放光。一照眾生苦。二生希有以。三感召有緣。四滅生死闇。

Sūtra: “Whereupon from his mouth he emitted immeasurable light.” Commentary: The third [point is] emitting light. Because he wished to expound the radiance of the precepts, he emitted light from his mouth. Light was emitted for four reasons: first, to illuminate the suffering of sentient beings; second, to inspire wonder; third, to summon those who have affinity; fourth, to extinguish the darkness of birth and death.