大般涅槃經集解 5.110

5.110

案僧亮曰：非無所益，亂心迷道，非行者所宜。當觀其身，釋無益之旨也。汝身是所應，所應既不得，住應豈得住耶？寶亮曰：雜毒者，昔教生解，因果未分，亦言雜毒。就今經而談，金剛以下雖明解非毒，而其體與苦未相分，故亦言雜毒。

Sengliang comments: It is not that it brings no benefit; but disturbing the mind and being confused about the Way is not appropriate for a practitioner. "You should contemplate your body" explains the principle of it being of no benefit. Your body is that which is responded to; since that which is responded to cannot remain, how could the responsive one remain? Baoliang comments: Regarding "mixed poison": in the past teaching, when generating understanding, cause and fruit were not yet distinguished, which was also called mixed poison. In terms of the present sūtra, from the adamantine [concentration] downward, although clear understanding is not poison, its substance is not yet distinguished from suffering, and so it is also called mixed poison.