俱舍論頌疏論本 5.12

5.12

後靜慮者，明所依地。修無想定，依第四禪，於靜慮中最居後故。求脫者，明作意也。謂諸外道計無想果為真解脫，為求彼故，修無想定。

'The final dhyāna' clarifies the ground upon which it relies. Cultivation of the absorption of non-conception relies on the fourth dhyāna, because among the dhyānas it is the very last. 'Seeking liberation' clarifies the mental orientation (manaskāra). It means that tīrthikas consider the result of non-conception to be true liberation, and in order to seek that, they cultivate the absorption of non-conception.