俱舍論疏 5.153

5.153

論「豈不經說至之有為相」，問也。經說有三，因何說四？答中有二：一不說住相；二住、異合說。

On the passage in the śāstra from “Do not the sūtras state…” to “…characteristics of the conditioned?”: This is a question. The sūtra speaks of three; why does [the treatise] speak of four? In the answer there are two points: first, that it does not speak of the characteristic of duration; second, that duration and difference are spoken of together.