One verse

Srimad Bhagavatam 12.6.42

12.6.42

तस्य ह्यासंस्त्रयो वर्णा अकाराद्या भृगूद्वह । धार्यन्ते यैस्त्रयो भावा गुणनामार्थवृत्तय: ॥ ४२ ॥

tasya hy āsaṁs trayo varṇā a-kārādyā bhṛgūdvaha dhāryante yais trayo bhāvā guṇa-nāmārtha-vṛttayaḥ

tasya
of that oṁkāra
hi
indeed
āsan
came into being
trayaḥ
three
varṇāḥ
sounds of the alphabet
a-kāra-ādyāḥ
beginning with the letter a
bhṛgu-udvaha
O most eminent of the descendants of Bhṛgu
dhāryante
are sustained
yaiḥ
by which three sounds
trayaḥ
the threefold
bhāvāḥ
states of existence
guṇa
the qualities of nature
nāma
names
artha
goals
vṛttayaḥ
and states of consciousness

Oṁkāra exhibited the three original sounds of the alphabet — A, U and M. These three, O most eminent descendant of Bhṛgu, sustain all the different threefold aspects of material existence, including the three modes of nature, the names of the Ṛg, Yajur and Sāma Vedas, the goals known as the Bhūr, Bhuvar and Svar planetary systems, and the three functional platforms called waking consciousness, sleep and deep sleep.