俱舍論記 22.80

22.80

「又契經言至故成顛倒」者，通第三經，一開三章、二別牒釋。此即開章。經言於苦謂樂倒者，此別意說，以諸世間，一於諸樂受、二於諸妙欲、三於諸三有一分樂中，一向計樂故成顛倒，非計少樂名為顛倒。

As for "Furthermore, a sūtra says... therefore it becomes an inversion": this resolves the third sūtra, first laying out three sections and second taking them up and explaining them separately. This lays out the sections. When the sūtra says that taking suffering to be pleasure is an inversion, this is spoken with a particular intent: because worldly beings exclusively imagine pleasure first with respect to pleasant feelings, second with respect to exquisite sensual desires, and third with respect to a portion of pleasure in the three realms of existence, it therefore becomes an inversion; it is not that imagining a minor pleasure is termed an inversion.