金剛經纂要刊定記 6.169

6.169

見聞不及。經文可見。然恐空生更約說法比知如來，故言音聲求之不得。此疑即從第十八中來，今預遮防故無後說。

Seeing and hearing cannot reach it. The sūtra text is clear. However, fearing Subhūti might further infer and know the Tathāgata through the expounding of Dharma, it therefore says that seeking him through voice and sound cannot attain him. This doubt comes from the eighteenth [doubt]; it is pre-emptively prevented now, so there is no subsequent exposition.