四分律行事鈔資持記 2.181

2.181

初答為二，先明作須無作。作休不防者，以作短故；不可常作者，心或餘用故。次若單下，明無作須作。二下，結示。

The first answer has two [parts]: first, clarifying that action requires non-action. "When action rests, it does not guard" is because action is brief; "it cannot always be acting" is because the mind may have other functions. Next, from "If merely..." downward, clarifying that non-action requires action. From "Both..." downward, concluding and indicating [this].