Mahabharata 13.75.30

13.75.30

iti nṛpa satataṃ gavāṃ pradāne yavaśakalānsaha gomayaiḥ pibānaḥ |
kṣititalaśayanaḥ śikhī yatātmā vṛṣa iva rājavṛṣastadā babhūva || 30 ||

"Vaisampayana continued, 'Thus addressed by Bhishma on the subject of properly making gifts of kine, king Yudhishthira did all that Bhishma wished. Verily, king Yudhishthira bore in mind the whole of that religion which the preceptor of the deities imparted unto the royal Mandhatri. Yudhishthira from that time began to make always gifts of kine and to support himself on grains of barley and on cowdung as both his food and drink. The king also began to sleep from that day on the bare earth, and possessed of restrained soul and resembling a bull in conduct, he became the foremost of monarchs. The Kuru king from that day became very attentive to kine and always worshipped them, hymning their praises. From that day, the king gave up the practice of yoking kine unto his vehicles. Wheresoever he had occasion to go, he proceeded on cars drawn by horses of good mettle.'"