Vishnupurana 3.2.51

3.2.51

tāvatpramāṇā ca niśā tato bhavati sattama
brahmarūpadharaḥ śete śeṣāhāv ambusaṃplave //

An entire Kalpa, oh Brahman, is said to comprise a thousand ages, or fourteen Manwantaras; and it is succeeded by a night of similar duration; during which, he who wears the form of Brahmá, Janárddana, the substance of all things, the lord of all, and creator of all, involved in his own illusions, and having swallowed up the three spheres, sleeps upon the serpent Śesha, amidst the ocean. Being after that awake, he, who is the universal soul, again creates all things as they were before, in combination with the property of foulness (or activity): and in a portion of his essence, associated with the property of goodness, he, as the Manus, the kings, the gods, and their Indras, as well as the seven Rishis, is the preserver of the world. In what manner Vishńu, who is characterised by the attribute of providence during the four ages, effected their preservation, I will next, Maitreya, explain.