瑜伽論記 13.169

13.169

言無記性攝者，補闕云：前已明是異熟所攝，即是無記，何須重辨？是無記性者，以次前明受數，是不苦不樂，以不苦樂受，通於三性，然未知此受，是何性攝？故今重明是無記性攝。

Regarding the statement that they are subsumed under the indeterminate nature: The Supplement says: It was already clarified earlier that they are subsumed under ripening, which is precisely indeterminate; why must this be explained again? They are of the indeterminate nature because just prior to this, the mental factor of feeling was explained as neither-painful-nor-pleasant; since neither-painful-nor-pleasant feeling runs through the three natures, and it was not yet known which nature this feeling is subsumed under, it is now explained again that it is subsumed under the indeterminate nature.