Mandukya Karika, verse 4.97

अणुमात्रेऽपि वैधर्म्ये जायमानेऽविपश्चितः |
असंगता सदा नास्ति किमुताऽऽवरणच्युतिः ॥ ९७ ॥

aṇumātre'pi vaidharmye jāyamāne'vipaścitaḥ |
asaṃgatā sadā nāsti kimutā''varaṇacyutiḥ || 97 ||

97. The slightest idea of variety (in Ātman) entertained by the ignorant bars their approach to the unconditioned. The destruction of the veil (covering the real nature of Ātman) is out of the question.

Shankara Bhashya (commentary)

If persons, through ignorance, think,—as those who differ from us assert—that an entity (i.e., Jīva or Ātman) does undergo the slightest change, either subjectively or objectively, then such ignorant persons can never realise the ever-unrelatedness (of Ātman).¹ Therefore² it goes without saying that there cannot be any destruction of bondage (that is supposed to keep the Jīva bound to the world).

Anandagiri Tika (glossary)

Accordingly the Ultimate Reality is immutable and non-dual Self. Knowledge is ever unrelated to objects as they do not, as such, exist. The view of the opponent regarding the separate existence of objects cannot be upheld as it contradicts the unrelated nature of Ātman which is admitted by all schools of thought.

¹ Ātman, etc.—If the birth or production of an object be admitted, knowledge must be related to it. Otherwise one cannot know its birth. In that case the absolute and unrelated nature of knowledge cannot be maintained.

² Therefore, etc.—If it be contended that knowledge is produced or if it be said that knowledge (Consciousness or Ātman) is not birthless by nature, then one cannot speak of liberation or the destruction of bondage, as there is no guarantee of the liberation being permanent.