八識規矩補註 2.23

2.23

此言第八識因中，於三性則唯無覆無記性，以不與煩惱俱故，平等無違拒故，是所熏故。此識緣境之時，相應心所唯遍行五，餘互違故。何則？無記性非善非惡，非善則善所不與相應，非惡則惡所亦不與之相應，所以互相違也。

This states that during the causal stage of the eighth consciousness, among the three natures it is solely of the anivṛtāvyākṛta nature, because it is not accompanied by afflictions, is impartial without conflict or resistance, and is that which is perfumed. When this consciousness cognizes an objective realm, its corresponding caittas are only the five sarvatragas, because the others are mutually contradictory. Why? The avyākṛta nature is neither wholesome nor unwholesome: if not wholesome, wholesome caittas do not correspond with it; if not unwholesome, unwholesome caittas also do not correspond with it; this is why they are mutually contradictory.