Vishnupurana 3.1.p12

3.1.p12

In the next Manwantara Vishnu was born of Vikunthi, as Vaikuntha along with the celestials called Vaikunthas. In the present period Vishnu was again born as Vamana the son of Kasyapa by Aditi. With three paces he conquered the worlds and having released them from all disturbances he gave them to Purandara. By these seven persons, in the various Manwantaras, the created beings have been preserved. He is called Vishnu because his energy pervades the whole world from the root Vis to 'enter' or 'pervade:' and all the celestials, the Manus, the kings of the gods are but the impersonations of the power of Vishnu.