俱舍論記 5.105

5.105

「謂有別法至說名為壽」者，答。能持煖、識，明有別壽，引經證用。經說三法能持於身，若三捨身身便僵仆。仰死名僵，伏死名仆，亦有側死且言僵仆，或從多說。故有別法能持煖、識相續住因，說名為壽。

On [the text reading]: "It refers to a separate dharma ... is called lifespan": This is the answer. Being able to sustain warmth and consciousness clearly indicates there is a separate lifespan, citing the sūtra to prove its function. The sūtra states that three dharmas are able to sustain the body; if the three abandon the body, the body then falls stiff. Dying facing upward is called 'stiff' (jiang), and dying face down is called 'prostrate' (pu); there is also dying on one's side, which is tentatively spoken of as stiff and prostrate, or it is stated according to the majority. Therefore there is a separate dharma that can sustain warmth and consciousness as the cause of their continuous abiding, which is called lifespan.