首楞嚴義疏注經 10.92

10.92

念念滅處，名互互無，以心纔生即滅，無體可得。行既如是，諸法亦然，故云因無得證。故有問者，但答無耳。

Where there is cessation from moment to moment is called 'each mutually ceases', because as soon as the mind arises it ceases, with no substance to be found. Since formations are like this, all dharmas are also thus, hence it says 'through nonexistence attains realization'. Therefore, when asked, he only answers 'no'.