金光明經文句記 2.160

2.160

二、「法性」下，明壽。色心和合乃有報得連持壽命。身既非陰，豈有命根？為物彊指不遷為壽。

Second, from "Dharma-nature" onward: explaining the lifespan. Only when form and mind unite is there a retributively obtained, continuously sustained lifespan. Since the body is not the aggregates, how could there be a life faculty? For sentient beings' sake, non-transience is forcefully designated as lifespan.