Vishnupurana 1.2.69

1.2.69

sa eva sarvabhūtātmā viśvarūpo yato 'vyayaḥ /
sargādikaṃ tu tasyaiva bhūtasthamupakārakam //

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.