Mbh 12.343.2a

"'The highly and holy one said, "I shall recite to thee, O son of Pandu, an ancient story of incidents originating from my own energy. Do thou listen to it with rapt attention! When four thousand Yugas according to the measure of the celestials elapse, the dissolution of the universe comes. The Manifest disappears into the Unmanifest. All creatures, mobile and immobile, meet with destruction. Light, Earth, Wind, all disappear. Darkness spreads over the universe which becomes one infinite expanse of water. When that infinite waste of water only exists like Brahma without second, it is neither day nor night. Neither aught nor naught exists; neither manifest nor unmanifest. Then only undifferentiated Brahman existed. When such is the condition of the universe, the foremost of Beings, viz., springs from Tamas, the eternal and immutable Hari that is the combination of the attributes (of omnipotence and the rest), belonging to Narayana, that is indestructible and immortal, that is without senses, that is inconceivable and unborn, that is Truth's self fraught with compassion, that is endued with the form of existence which the rays of the gem called Chintamani have, that causes diverse kinds of inclinations to flow in diverse directions, that is divested of the principles of hostility and deterioration and mortality and decay, that is formless and all-pervading, and that is endued with the principle of universal Creation and of Eternity without beginning, middle, or end. There is authority for this assertion. The Sruti declares,--'Day was not. Night was not. Aught was not. Naught was not. In the beginning there was only Tamas[1854] in the form of the universe, and she is the night of Narayana of universal form.' Even this is the meaning of the word Tamas. From that Purusha (called Hari), thus born of Tamas and having Brahman for his parent, started into existence the Being called Brahman.