大般涅槃經集解 2.35

2.35

案僧亮曰：聲至有頂，語其上聞。光遍十方，語其四遠。二文互出，事表未殊也。法瑤曰：口出其光，以表最極妙說之相也。僧宗曰：此第二相也。上以音聲生解，此從光明得悟也。門以通為義，故以口為面門也。寶亮曰：種種色光者，昔經亦有此瑞，但出經者表佛威光，故以種種為名也。智秀曰：向雖聞聲，未測所之，是以放光示令知也。

Sengliang states: The sound reached the Summit of Existence, speaking of its being heard above. The light pervaded the ten directions, speaking of its fourfold distance. The two passages alternate with each other, but what they express is not different.
Fayao states: The light emitted from his mouth expresses the mark of the most ultimate, wondrous teaching.
Sengzong states: This is the second mark. Above, understanding was generated through sound; here, awakening is attained through light. "Gate" takes passage as its meaning; hence the mouth is the gate of the face.
Baoliang states: Regarding the lights of various colours: past sūtras also had this auspicious sign, but the one who produced the sūtra expressed the Buddha's majestic radiance; hence it is named "various".
Zhixiu states: Previously, although they heard the voice, they did not know where [it came from]; therefore he emitted light to show them and make them know.