金剛經纂要刊定記 3.40

3.40

於此下。釋通。於此者論云於法也。能覺者定通，能說者說通也。意云定通方得說通，以散心說法不能如實，從定發言必有當也。故下文云：云何為人演說不取於相如如不動？諸經之中每欲說法皆先入定，意皆如此云云。斯亦示現為後軌也。若準如來，言念何失，是故論云顯示等也。

The passage beginning "In this..." explains and resolves it. "In this" means in the treatise, "in the Dharma." Being able to awaken is mastery of samādhi; being able to speak is mastery of exposition. The meaning is that only through mastery of samādhi does one attain mastery of exposition, for expounding the Dharma with a distracted mind cannot be in accordance with reality; words uttered from samādhi will certainly hit the mark. Therefore, the text below says: "How should one explain it for others? Without grasping at signs, like like-suchness, unmoving." Whenever the Buddha wished to expound the Dharma across the various sūtras, he always entered samādhi first, and the intent was always like this. This too is a manifestation to serve as a model for posterity. If according to the Tathāgata, what error could there be in speech and thought? Therefore, the treatise says it displays this, and so forth.