Mbh 12.36.1e

One should, therefore, always achieve acts that are righteous and abstain altogether from those that are unrighteous. I have now indicated what the expiations are of the sins that have been mentioned. There is expiation for every sin except those that are called Mahapatakas (highly heinous sins). As regards sins in respect of unclean food and the like, and improper speeches, etc., they are of two classes, viz., those committed consciously and those that are committed unconsciously. All sins that are committed consciously are grave, while those that are committed unconsciously are trivial or light. There is expiation for both. Indeed sin is capable of being washed away by (observance of) the ordinances spoken of. Those ordinances, however, have been laid down only for believers (in God) and those that have faith. They are not for atheists or those that have no faith, or those in whom pride and malice predominate. A person, O tiger among men, that is desirous of weal both here and hereafter, should, O foremost of virtuous men, have recourse to righteous behaviour, to (the counsels of) men that are righteous, and to the duties that have been ordained for him. Therefore, for the reasons already advanced (by me), thou, O king, shalt be cleansed of all thy sins for thou hast slain thy foes in the discharge of thy duties as a king and for the protection of thy life-breath and thy inheritance. Or, if not withstanding this, thou still regardest thyself to be sinful, perform expiation. Do not cast away thy life in consequence of such grief that is not becoming a wise man."'