Mbh 13.106.4c

Listen now, O king, to me as I tell thee what the rules are in respect of each of the lunar days. The man who, abstaining from it every day, takes rice at the expiration of every fortnight, becomes possessed of a great many kine, a large progeny, and a long life. He who observes a fast for three nights every month and conducts himself thus for two and ten years, attains to a position of supremacy among his kinsmen and associates, without a rival to contest his claim and without any anxiety caused by any one endeavouring to rise to the same height. These rules that I speak of, O chief of Bharata's race, should be observed for two and ten years. Let the inclination be manifested towards it. That man who eats once in the forenoon and once after evening and abstains from drinking (or eating anything) in the interval, and who observes compassion, towards all creatures and pours libations of clarified butter on his sacred fire every day, attains to success, O king, in six years. There is no doubt in this. Such a man earns the merit that attaches to the performance of the Agnishtoma sacrifice. Endued with merit and freed from every kind of stain, he attains to the region of the Apsaras that echo with the sound of songs and dance, and passes his days in the company of a thousand damsels of great beauty. He rides on a car of the complexion of melted gold and receives high honours in the region of Brahma. After the exhaustion of that merit such a person comes back to earth and attains to pre-eminence of position. That man who passes one whole year, confining himself every day to only one meal, attains to the merit of the Atiratra sacrifice. He ascends to heaven after death and receives great honours there. Upon the exhaustion of that merit he returns to earth and attains to a position of eminence.