俱舍論疏 2.37

2.37

論「有雖無用至定當死者」，答也。根之有無，非定由有用，無用亦生。如處六處胞胎定當死者，此眼等根雖是無用，亦有根生。鼻、舌亦爾。

The treatise says: "Although some have no function... those destined to die." This is the answer. The presence or absence of faculties is not determined solely by their having a function; they also arise without a function. Just as in the case of one in the womb with the six bases who is destined to die, although these faculties of the eye and so forth have no function, the faculties still arise. The nose and tongue are likewise.