俱舍論記 13.3

13.3

〈分別業品〉者，造作名業，此品廣明，故名分別。所以次明業者，前品明果、此品明因，果不孤起必藉因生，望果是親故次說業。

Regarding "Karma-nirdeśa": action is called karma; because this chapter explains it in detail, it is called "nirdeśa" (exposition). As for why karma is explained next: the preceding chapter explained the result, and this chapter explains the cause. Results do not arise in isolation but necessarily depend on causes to arise; because it is proximate to the result, karma is explained next.