Mbh 12.341.4a

"Vaisampayana said, 'The question thou has asked me, O ruler of men, relates to a deep mystery. No man that has not undergone penances, and that is not acquainted with the Puranas, can speedily answer it. I shall, however, answer thee by reciting to thee what my preceptor the Island-born Krishna, otherwise called Vyasa, the great Rishi who has classified the Vedas, had said unto us on a former occasion when questioned by us. Sumanta, and Jaimini, and Paila of firm vows, and myself numbering the fourth, and Suka forming the fifth, were disciples of the illustrious Vyasa. We numbering five in all, endued with self-restraint and purity of observances, had completely subjugated wrath and controlled our senses. Our preceptor used to teach us the Vedas, having the Mahabharata for their fifth. Once on a time, while we were engaged in studying the Vedas on the breast of that foremost of mountains, viz., the delightful Meru, inhabited by Siddhas and Charanas, this very doubt arose in our minds that has been expressed by thee today. We, therefore, questioned our preceptor about it. I heard the answer that our preceptor made. I shall now recite that answer to thee, O Bharata. Hearing these words that were addressed to him by his disciples that dispeller of all kinds of darkness represented by ignorance, viz., the blessed Vyasa, the son of Parasara, said these words: "I have undergone very severe, in fact, the austerest of penances. Ye best of men, I am fully conversant with the Past, the Present, and the Future. In consequence of those penances of mine and of the restraint under which I kept my senses while I dwelt on the shores of the Ocean of milk, Narayana became gratified with me. As the result of the great God's gratification, this omniscience with respect to the Past, the Present, and the Future, that was desired by me, arose in my mind. Listen now to me as I discourse to you, in due order, on this great doubt that has disturbed your minds.