俱舍論疏 22.122

22.122

論「然經中說至及彼因因」，會彼兩經說不同也。愛為因故者，偏說起因。業、愛、無明者，具說三因，業為生因、愛為起因、無明為因因。愛為業因，無明與愛能為因故，故曰因因。

On the Śāstra's 'However, what is stated in the sūtra [...] and its cause of cause': Reconciling the different statements of the two sūtras. 'Because craving is the cause' specifically speaks of the cause of arising. 'Karman, craving, and ignorance' fully speaks of the three causes: karman is the cause of birth (janmahetu), craving is the cause of arising (samutthāpahetu), and ignorance is the cause of the cause (hetuhetu). Craving is the cause of karman, and ignorance can be the cause of craving; therefore it is called 'cause of cause'.