金光明經文句 1.18

1.18

「無量甚深」者，將明游入，簡顯其體高廣、體包法界，故言無量。徹到三諦，故言甚深。非是二乘下地菩薩之所逮及，故言無量甚深也。

Regarding "immeasurably profound": being about to clarify roaming and entering, to differentiate and reveal its substance as lofty and broad, with substance encompassing the Dharmadhātu, it therefore says "immeasurable." Penetrating through to the three truths, it therefore says "profound." It is not what the two vehicles and lower-stage bodhisattvas can reach; hence it says "immeasurably profound."