Vishnupurana 1.2.63

1.2.63

tamodrekī ca kalpānte rudrarūpī jarnādanaḥ /
maitreyākhilabhūtāni bhakṣayatyatidārūṇaḥ //

Affecting then the quality of activity, Hari, the lord of all, himself becoming Brahmá, engaged in the creation of the universe. Vishńu with the quality of goodness, and of immeasurable power, preserves created things through successive ages, until the close of the period termed a Kalpa; when the same mighty deity, Janárddana, invested with the quality of darkness, assumes the awful form of Rudra, and swallows up the universe. Having thus devoured all things, and converted the world into one vast ocean, the Supreme reposes upon his mighty serpent couch amidst the deep: he awakes after a season, and again, as Brahmá, becomes the author of creation.