大方廣圓覺修多羅了義經略疏 1.958

1.958

據此三難，諸典無文；唯佛了知，登地方受。今乃請宣成教，普示末世凡夫，故曰無遮。開祕密藏，祕謂非器不傳，密謂覆相而說。

With respect to these three challenges, there is no text in the various treatises; only the Buddha fully knows it, and only upon ascending the bhūmis is it received. Now he requests the proclamation of the established teaching to show it universally to ordinary people of the final age; hence it is called "unimpeded." As for "opening the secret treasury," "secret" (bì) means not transmitting it to those who are not proper vessels, and "esoteric" (mì) means speaking by concealing marks.