Vishnupurana 3.2.57

3.2.57

cakravartisvarūpeṇa tretāyām api sa prabhuḥ
duṣṭānāṃ nigrahaṃ kurvan paripāti jagattrayam //

In the Krita age, Vishńu, in the form of Kapila and other inspired teachers, assiduous for the benefit of all creatures, imparts to them true wisdom. In the Treta age he restrains the wicked, in the form of a universal monarch, and protects the three worlds. In the Dwápara age, in the person of Veda-vyása, he divides the one Veda into four, and distributes it into innumerable branches: and at the end of the Kali or fourth age he appears as Kalki, and reestablishes the iniquitous in the paths of rectitude. In this manner the universal spirit preserves, creates, and at last destroys, all the world.