瑜伽師地論略纂 11.104

11.104

論二世樂中，「有九種」者，即遮止、開許、攝受、調伏為四，不取身口二業也；及五度，不論戒度。此九即戒度故也。

In the treatise's explanation of the happiness of the two worlds, where it says "there are nine kinds," these are: prohibition, permission, gathering in, and taming, which make four—without taking physical and vocal actions; and the five perfections, without counting the perfection of morality. These nine are included precisely because they are the perfection of morality.