Mbh 14.54.2b

Know, O best of regenerate person, that Dharma is my eldest-born offspring, sprung from my mind, O learned Brahmana, whose essence is compassion for all creatures. Constantly transforming myself, I take birth in diverse wombs, O best of men, for upholding that son of mine, with the aid of men now existing in or departed from the world. Indeed, I do this for protecting Righteousness and for establishing it. In those forms that I assume for the purpose, I am known, O son of Bhrigu's race, in the three worlds as Vishnu and Brahman and Sakra. I am the origin and I am the destruction of all things. I am the creator of all existent objects and I am their destroyer. Knowing no change myself, I am the destroyer of all those creatures that live in sinfulness. In every Yuga I have to repair the causeway of Righteousness, entering into diverse kinds of wombs from desire of doing good to my creatures. When, O son of Bhrigu's race, I live in the order of the deities, I then verily act in every respect as a deity. When I live in the order of the Gandharvas, I then, O son of Bhrigu's race, act in every respect as a Gandharva. When I live in the order of the Nagas, I then act as a Naga, and when I live in the order of Yakshas or that of Rakshasas, I act after the manner of that order. Born now in the order of humanity, I must act as a human being. I appealed to them (the Kauravas) most piteously. But stupefied as they were and deprived of their senses, they refused to accept my words. I frightened them, filled with wrath, referring to some great fear (as the consequence of their slighting my message). But once more I showed themselves my usual (human) form. Possessed as they were of unrighteousness, and assailed by the virtue of Time, all of them have been righteously slain in battle, and have, without doubt, gone to Heaven. The Pandavas also, O best of Brahmanas, have acquired great fame. I have thus told thee all that thou hadst asked me."'"