俱舍論記 22.68

22.68

「威儀易脫理亦應然」者，此類釋也。行、住、坐、臥威儀易脫，諸有情類計為樂因。此若非時、或復過量，成苦因等，准前應釋。此顯威儀樂因不定，明無實樂。

Regarding "The alternation of postures by reason should also be like this": this is an analogous explanation. The alternation of the postures—walking, standing, sitting, and lying down—is conceptualized by sentient beings as a cause of pleasure. If this is out of season or excessive, it becomes a cause of suffering, etc., which should be explained following the above. This shows that the pleasure-cause of bodily postures is variable, clarifying that there is no real pleasure.