金剛經纂要刊定記 4.229

4.229

無定法。經徵意云：以何義故，無定法可說耶？釋意云：欲言其有無狀無名，欲言其無聖以之靈。諦理若此，欲何說哉？說尚不得，欲何取哉？取即得也，是故上云：「無有定法如來可說」等。

On 'No fixed phenomenon': The sūtra's question means: 'For what reason is there no fixed phenomenon that can be spoken of?' The explanation means: 'If one wishes to speak of its existence, it has no shape and no name; if one wishes to speak of its non-existence, the sages are made numinous by it. When the truth of principle is like this, what can one speak of? When even speaking is impossible, what could one grasp? Grasping is attainment; therefore above it says: "There is no fixed phenomenon that the Tathāgata can speak of"' and so forth.