觀音玄義記 1.6

1.6

言「化無所化」者，據性平，等忘於化功。雖令九道皆趣涅槃，而無眾生得滅度者。平等真法界，佛不度眾生，終日化物，終日無化。

As for "transformation has nothing to be transformed": based on the equality of nature, one forgets the work of transformation. Although causing the nine realms to all proceed toward nirvāṇa, yet there are no sentient beings who attain extinction. In the equal, true dharmadhātu, the Buddha does not deliver sentient beings; all day long transforming beings, yet all day long there is no transformation.