成唯識論述記 4.514

4.514

述曰：下難有五：初難云：是則不應說心行滅，心行定中無，出定方始有。即說定中心行滅，轉識定中無，出定方始有，何為說不離？應說定中識體非有，何乃說識不離於身？識與想等生滅同故。以汝想等名大地故，比量可知。

The Commentary states: Below there are five objections. The first objection states: In that case, one should not say that mental activities are extinguished. Mental activities are absent during attainment and only exist upon emerging from attainment, yet it is said that mental activities are extinguished during attainment; the evolving consciousnesses are absent during attainment and only exist upon emerging from attainment, so why say that they do not depart? One should say that during attainment the entity of consciousness does not exist; why instead say that consciousness does not depart from the body? Because the arising and ceasing of consciousness and of perception, etc., are identical. Since your perception and so on are termed mahābhūmikas, the inference can be known.