成唯識論述記 6.344

6.344

述曰：外人徵曰：勤體唯能遍策勵善心，三根但能為善法依，依是根義，如何說此四法有防、修用？

The Commentary states: The opponent inquires: 'The substance of zeal is solely able to universally spur wholesome minds, and the three roots can only serve as the basis for wholesome dharmas—