The Mandukya Upanishad with Gaudapada’s Karika and Shankara’s Commentary
Kārikā, verse 1.22
त्रिषु धामसु यस्तुल्यं सामान्यं वेत्ति निश्चितः ।
स पूज्यः सर्वभूतानां वन्द्यश्चैव महामुनिः ॥ २२ ॥
triṣu dhāmasu yastulyaṃ sāmānyaṃ vetti niścitaḥ |
sa pūjyaḥ sarvabhūtānāṃ vandyaścaiva mahāmuniḥ || 22 ||
22. He who knows without doubt, what the ‘common features’ are in the three states, is worshipped and adored by all beings and he is also the greatest sage.
Ānandagiri’s Ṭīkā (glossary):
1 Common features—That is, the three quarters of Ātman, viz., Viśva, Taijasa and Prājña associated with waking, dream and deep sleep states are identical with the three sounds (letters) of Aum, viz., A, U and M respectively for reasons stated above.
2 Knower, etc.—The knower of this identity is highly extolled for this reason: From the standpoint of Ātman, Viśva merges in Taijasa and Taijasa in Prājña; similarly from the standpoint of Aum the sound A merges in U and U merges in M. The quarters of Ātman are identical with the sound of M. He who knows this identity also knows that the entire universe of the dream and waking experiences emerges from and merges into Prājña. This Prājña is Brahman though it appears as the causal self to those whose mind still moves in the plane of causality. It is only the knower of Brahman that knows Prājña also as Turīya.