大方廣佛華嚴經隨疏演義鈔 79.76

79.76

疏「然佛尚不說」下，第四謙退結成。佛尚不說者，即此經云「心意識皆不可得」，是不說也。「釋迦掩室於摩竭，淨名杜口於毘耶」，皆佛不說也。果海離言，唯證相應，皆不可說。「有因緣故」者，即四悉檀。因緣則得無說之說耳。

Regarding the commentary's statement from "Yet even the Buddha does not speak of it" downward: this is the fourth part, a humble concluding summary. "Even the Buddha does not speak of it" refers to this sūtra saying that "mind, thought, and consciousness are all unapprehensible," which is non-speaking. "Śākyamuni shut himself in a room in Magadha; Vimalakīrti closed his mouth in Vaiśālī"—these are both the Buddha's non-speaking. The ocean of the fruit transcends speech and is accorded with only in realization; all are ineffable. "Because there are causes and conditions" refers to the four siddhāntas. Through causes and conditions, there is the speech of non-speaking.