金剛經纂要刊定記 4.241

4.241

有言下。釋也。此乃以說反驗於證。且川有珠而不枯，山有玉而增潤。內無德本，外豈能談？故但言說，自表其證也。又此言取即是證也。

[The passage beginning] "Having speech..." explains it. This is inferring realization from exposition. Indeed, when a river contains pearls it does not dry up, and when a mountain contains jade its moisture increases. If one has no root of virtue within, how could one speak outwardly? Thus, merely mentioning exposition self-evidently reveals realization. Furthermore, the word "grasping" here is itself realization.