瑜伽論記 7.94

7.94

界善巧中，若復於彼十八種法乃至名界善巧者，十八界體正取，能生種子以為界。

In skillfulness in the elements: 'If, furthermore, with regard to those eighteen dharmas... up to is called skillfulness in the elements': the entity of the eighteen elements properly takes the seeds capable of producing them as the elements.