大般涅槃經義記 7.244

7.244

二「若使涅槃是聲果」下破邪顯正，若是聲果，本無今有，方便修生故非常法。

Second, from "If nirvāṇa were a fruit of sound..." onward refutes the heterodox and reveals the correct: if it were a fruit of sound, having previously been non-existent and now existing, generated through the cultivation of expedient means, it would not be an eternal dharma.