大乘百法明門論開宗義決 1.242

1.242

恒不恒行心等滅者。末那識性即是恒行。若第六識是不恒行。其無想定是有漏故。令不恒行心心法滅。此滅盡定是無漏故。非但不恒心心法滅。恒行一令染污亦除。言恒不恒心等皆滅。非謂末那淨分亦滅。

Regarding "the cessation of the constantly and not constantly functioning minds, etc.": the nature of the manas consciousness is precisely constantly functioning, whereas the sixth consciousness is not constantly functioning. Because the absorption of non-conception is contaminated, it causes the not constantly functioning mind and mental factors to cease. Because this absorption of cessation is uncontaminated, not only do the not constantly functioning mind and mental factors cease, but the defilements of the constantly functioning one are also eliminated. Stating that the constantly and not constantly functioning minds and so forth all cease does not mean that the pure portion of the manas also ceases.