俱舍論記 13.168

13.168

「何法何性由何因成」者，復作三問：一問於諸法中何法名為勝義等四；二問此勝義等於三性中復是何性；三問此勝義等由何因故得成善等。

Regarding "What dharma is of what nature by what cause constituted?": this raises three questions again: first, asking what dharmas among all dharmas are called the four such as the ultimate; second, asking what nature these four, the ultimate and the rest, are among the three natures; third, asking by what cause these four, the ultimate and the rest, are able to become good and so forth.