俱舍論記 13.173

13.173

「等起善者至所引生乳」者，釋第四句，明等起善。謂身、語業不相應行，即是四相、得及二定，以是自性及相應善所等起故。此等起善，如良藥汁所引生乳。謂如牸牛飲甘草汁，由此力故所引生乳其味甘美。

Regarding the passage from "Good by origination" up to "milk brought forth": this explains the fourth line, clarifying what is good by origination (samuṭṭhāna-kuśala). This refers to bodily and vocal actions and the formations non-associated with mind—namely, the four characteristics [of saṃskāras], acquisition (prāpti), and the two absorptions (samāpatti)—because they are equally originated by that which is good by intrinsic nature and good by association. This good by origination is like milk brought forth by medicinal sap: just as when a cow drinks liquorice sap, the milk brought forth by the power of this is sweet in taste.