首楞嚴義疏注經 10.199

10.199

實非能生執以為能，名能非能。摩䤈首羅，即大自在天，三目八臂，外道所宗為能生因也。現無邊身者，以執我能現起無量眾生也。因既能為，果成能事，因果相稱也。

Actually being incapable of producing yet grasping it as capable is called 'the capable and non-capable.' Maheśvara is the Great Sovereign Deva, with three eyes and eight arms, revered by non-Buddhists as the productive cause. 'Manifesting a boundless body' means that he grasps that he himself can manifest immeasurable sentient beings. Since in the cause he can act, in the fruit he accomplishes capable deeds; cause and fruit correspond to each other.