Mbh 13.141.12c

It is also his duty to perform sacrifices and other religious rites according to the ordinances laid down in the Vedas. Adherence to the practice of properly judging the disputes of litigants before him, and a devotion to truthfulness of speech, and interference for aiding the distressed, are the other duties by discharging which the king acquires great glory both here and hereafter. He should also lay down his life on the field of battle, having displayed great prowess on behalf of kine and Brahmanas. Such a king acquires in Heaven such regions of felicity as are capable of being won by the performance of Horse-sacrifices. The duties of the Vaisya always consist of the keeping of cattle and agriculture, the pouring of libations on the sacred fire, the making of gifts, and study. Trade, walking in the path of righteousness, hospitality, peacefulness, self-restraint, welcoming of Brahmanas, and renouncing things (in favour of Brahmanas), are the other eternal duties of the Vaisya. The Vaisya, engaged in trade and walking in the path of righteousness, should never sell sesame and perfumery and juices or liquid substances. He should discharge the duties of hospitality towards all. He is at liberty to pursue religion and wealth and pleasure according to his means and as much as is judicious for him. The service of the three regenerate classes constitutes the high duty of the Sudra. That Sudra who is truthful in speech and who has subdued his senses is regarded as having acquired meritorious penances. Verily, the Sudra, who having got a guest, discharges the duties of hospitality towards him, is regarded as acquiring the merit of high penances. That intelligent Sudra whose conduct is righteous and who worships the deities and Brahmanas, becomes endued with the desirable rewards of righteousness. O beautiful lady, I have thus recited to thee what the duties are of the four orders. Indeed, O blessed lady, I have told thee what their respective duties are.