俱舍論頌疏論本 6.43

6.43

釋曰：二世者，遍行同類唯通過、現二世也。三世三者，謂異熟相應俱有三因，通三世也。頌既不說能作因所居，義准應知，通三世非世，非世者無為也。

The explanation says: "Two time periods": universal and similar causes penetrate only two time periods, the past and the present. "Three [causes are of] three time periods": the three causes of maturation, association, and co-existence penetrate the three time periods. Since the verse does not state the locus of the efficient cause, by logical implication it should be known that it penetrates the three time periods and the non-temporal; the non-temporal refers to the unconditioned (asaṃskṛta).