Mandukya Karika, verse 4.61-62


यथा स्वप्ने द्वयाभासं चित्तं चलति मायया ।
तथा जाग्रद्द्वयाभासं चित्तं चलति मायया ॥ ६१ ॥
अद्वयं च द्वयाभासं चित्तं स्वप्ने न संशयः ।
अद्वयं च द्वयाभासं तथा जाग्रन्न संशयः ॥ ६२ ॥

yathā svapne dvayābhāsaṃ cittaṃ calati māyayā |
tathā jāgraddvayābhāsaṃ cittaṃ calati māyayā || 61 ||
advayaṃ ca dvayābhāsaṃ cittaṃ svapne na saṃśayaḥ |
advayaṃ ca dvayābhāsaṃ tathā jāgranna saṃśayaḥ || 62 ||

61-62. As in dream, the mind is seen to act through Māyā manifesting the appearance of duality, so also in the waking state the mind is seen to act, through Māyā, producing the appearance of duality.

There is no doubt that the mind which is, in fact, non-dual, appears as dual in dream; in like manner, undoubtedly, the waking state, which is non-dual, appears as dual.

Shankara Bhashya (commentary)

That pure consciousness which is non-dual (from the standpoint of the Supreme Reality) is sought to be described by words, is due to the active condition of the mind (which is due to Avidyā). This description (of the non-dual Ātman by words) has no meaning from the standpoint of the Ultimate Truth. These1 verses have already been explained.