Mbh 1.62.5a

“This work presents an account of the gods and royal sages and sacred regenerate Rishis, the sinless Kesava; the god of gods, Mahadeva and the goddess Parvati; the birth of Kartikeya who sprang from union of Parvati with Mahadeva and was reared by many mothers; the greatness of Brahmanas and of kine. This Bharata is a collection of all the Srutis, and is fit to be heard by every virtuous person. That learned man who reciteth it to Brahmanas during the sacred lunations, becometh cleansed of all sins, and, not caring for heaven as it were, attaineth to a union with Brahma. He that causeth even a single foot of this poem to be heard by Brahmanas during the performance of a Sraddha, maketh that Sraddha inexhaustible, the Pitris becoming ever gratified with the articles once presented to them. The sins that are committed daily by our senses or the mind, those that are committed knowingly or unknowingly by any man, are all destroyed by hearing the Mahabharata. The history of the exalted birth of the Bharata princes is called the Mahabharata. He who knoweth this etymology of the name is cleansed of all his sins. And as this history of the Bharata race is so wonderful, that, when recited, it assuredly purifieth mortals from all sins. The sage Krishna-Dwaipayana completed his work in three years. Rising daily and purifying himself and performing his ascetic devotions, he composed this Mahabharata. Therefore, this should be heard by Brahmanas with the formality of a vow. He who reciteth this holy narration composed by Krishna (Vyasa) for the hearing of others, and they who hear it, in whatever state he or they may be, can never be affected by the fruit of deeds, good or bad. The man desirous of acquiring virtue should hear it all. This is equivalent to all histories, and he that heareth it always attaineth to purity of heart. The gratification that one deriveth from attaining to heaven is scarcely equal to that which one deriveth from hearing this holy history.