Mandukya Karika, verse 4.41

Sanskrit text, IAST transliteration and English translation

विपर्यासाद्यथा जाग्रदचिन्त्यान्भूतवत्स्पृशेत् ।
तथा स्वप्ने विपर्यासात् धर्मास्तत्रैव पश्यति ॥ ४१ ॥

viparyāsādyathā jāgradacintyānbhūtavatspṛśet |
tathā svapne viparyāsāt dharmāstatraiva paśyati || 41 ||

41. As one in the waking state, through false knowledge, handles, as real, objects whose nature cannot be described; similarly; in dream also, one perceives, through false knowledge, objects whose existence is possible in that condition alone.

Shankara Bhashya (commentary)

This verse intends to remove the slightest possibility of the causal relation between the waking and the dream States, though both are unreal. As in the waking state, one, through want of proper discrimination, imagines the snake seen in place of the rope as real—the nature of which, in fact, cannot be really determined,—so also in dream, one, through want of discrimination, imagines as if one really perceives such objects as elephant, etc. These dream objects, such as elephants, etc., are peculiar to the dream condition alone; they are not the effect of the waking experiences.

Anandagiri Tika (glossary)

The nature, etc.—The snake seen in place of the rope cannot be called either existent or non-existent. If it be really existent then it cannot cease to exist. And if it be really non-existent then it cannot appear as existing. This is called Anirvachaniya or the indescribable nature of the sense-objects.