首楞嚴義疏注經 6.90

6.90

由我不觀所聽音聲，但觀聞性，音聲自寂，聞相無生，塵境不拘，自然解脫。自既如是，故令十方一切眾生聞我音聲即得度苦。

Because I did not observe the sound that was heard, but only observed the nature of hearing, sound spontaneously fell silent, the characteristics of hearing were free of arising, and unconstrained by the realm of dust, there was spontaneous liberation. Since I myself was like this, I cause all sentient beings in the ten directions, upon hearing my voice, immediately to obtain deliverance from suffering.