Vishnupurana 3.3.22

3.3.22

dhruvam ekākṣaraṃ brahma om ity evaṃ vyavasthitam
bṛhatvād bṛṃhaṇatvāc ca tad brahmety abhidhīyate //

The syllable Om is defined to be the eternal monosyllabic Brahma. The word Brahma is derived from the root Vriha (to increase), because it is infinite (spirit), and because it is the cause by which the Vedas (and all things) are developed. Glory to Brahma, who is addressed by that mystic word, associated eternally with the triple universe, and who is one with the four Vedas. Glory to Brahma, who, alike in the destruction and renovation of the world, is called the great and mysterious cause of the intellectual principle (Mahat); who is without limit in time or space, and exempt from diminution or decay; in whom (as connected with the property of darkness) originates worldly illusion; and in whom resides the end of soul (fruition or liberation), through the properties of light and of activity (or goodness and foulness). He is the refuge of those who are versed in the Sánkhya philosophy; of those who have acquired control over their thoughts and passions. He is the invisible, imperishable Brahma; varying in form, invariable in substance; the chief principle, self-engendered; who is said to illuminate the caverns of the heart; who is indivisible, radiant, undecaying, multiform. To that supreme Brahma be for ever adoration.