Vishnupurana 1.2.69

Thus the one only god, Janárddana, takes the designation of Brahmá, Vishńu, and Śiva, accordingly as he creates, preserves, or destroys. Vishńu as creator, creates himself; as preserver, preserves himself; as destroyer, destroys himself at the end of all things. This world of earth, air, fire, water, ether, the senses, and the mind; all that is termed spirit, that also is the lord of all elements, the universal form, and imperishable: hence he is the cause of creation, preservation, and destruction; and the subject of the vicissitudes inherent in elementary nature. He is the object and author of creation: he preserves, destroys, and is preserved. He, Vishńu, as Brahmá, and as all other beings, is infinite form: he is the supreme, the giver of all good, the fountain of all happiness.

Thus the one only god, Janárddana, takes the designation of Brahmá, Vishńu, and Śiva, accordingly as he creates, preserves, or destroys. Vishńu as creator, creates himself; as preserver, preserves himself; as destroyer, destroys himself at the end of all things. This world of earth, air, fire, water, ether, the senses, and the mind; all that is termed spirit, that also is the lord of all elements, the universal form, and imperishable: hence he is the cause of creation, preservation, and destruction; and the subject of the vicissitudes inherent in elementary nature. He is the object and author of creation: he preserves, destroys, and is preserved. He, Vishńu, as Brahmá, and as all other beings, is infinite form: he is the supreme, the giver of all good, the fountain of all happiness.