俱舍論疏 10.117

10.117

論「此成十八具足由三」，答也。由自性故，分為三受；由唯意相應故，唯取喜、憂、捨三，不取苦、樂；由所緣故，各分六種。由此十八不增減也。

[On the Śāstra's statement:] 'These become eighteen fully by virtue of three [factors]', this is the answer. By virtue of essential nature, they are divided into three feelings; by virtue of associating solely with the mind (manas), they take only the three of joy, grief, and equanimity, excluding suffering and pleasure; by virtue of cognitive objects, each is divided into six kinds. Due to this, the eighteen neither increase nor decrease.