俱舍論疏 6.238

6.238

論「第二無間至故成第三」，經部答也。聖人見第二諦，後見此滅故，說第二諦後說此滅故名為第三，非要有體方名第三。

[When] the treatise [states]: "Immediately following the second ... therefore it becomes the third," the Sautrāntika replies: "Because the noble person sees the second truth and subsequently sees this cessation, and because after speaking of the second truth this cessation is spoken of, it is termed the third; it does not require an entity to be called the third."