成唯識論述記 5.883

5.883

述曰：於中有二：初解因位受俱；後解果位受俱。因位中有二：初解本頌；後別分別。然此六識非如七、八，體皆易脫，恒不定故。易脫是間斷、轉變義；不定是欣、慼、捨行互起故，皆通三受，所以如文。

The Commentary states: Within this there are two parts: first, explaining association with feeling in the causal stage; later, explaining association with feeling in the fruitional stage. Within the causal stage there are two: first, explaining the root verse; later, distinct classifications. However, these six consciousnesses are not like the seventh and eighth: their substances are all easily altered and constantly unstable. 'Easily altered' means interrupted and mutable; 'unstable' means that the activities of joy, sorrow, and equanimity arise mutually, and therefore all are associated with the three feelings. The reasons are as given in the text.