瑜伽師地論略纂 16.78

16.78

論云「說因」者，說因者，因言所以。即謂外人曰即復有所以故不增長、無所以故不增長，即是成宗之因所以也。此中為比量，思之可解。

The treatise says, "states the reason": stating the reason refers to the cause, meaning the rationale. That is, it addresses the non-Buddhist opponent: there being a rationale it does not increase, or there being no rationale it does not increase; these are the reasons and rationales that establish the thesis. Within this, it serves as an inference (*anumāna*); if one contemplates it, it can be understood.