Mbh 12.269.3c

Without having acquired purity of heart which is the true result of all pious acts such as gifts and sacrifices, men of foolish understandings do not succeed in obtaining a knowledge of what is needed in making one a Brahmana even when explained by preceptors. Destitute of a knowledge of all this, these men desire fruits of a different kind, viz., heaven and its joys.[1249] Unable to practise even a small part of that good conduct which has come down from remote times, which is eternal, which is characterised by certitude, which enters as a thread in all our duties, and by adopting which men of knowledge belonging to all the modes of life convert their respective duties and penances into terrible weapons for destroying the ignorance and evils of worldliness, men of foolish understandings regard acts that are productive of visible fruits, that are fraught with the highest puissance, and that are deathless, as fruitless after all and as deviations (from the proper course) not sanctioned by the scriptures. In truth, however, that conduct, embracing as it does practices the very opposite of those that are seen in seasons of distress, is the very essence of heedfulness and is never affected by lust and wrath and other passions of a similar kind.[1250] As regards sacrifices again, it is very difficult to ascertain all their particulars. If ascertained, it is very difficult to observe them in practice. If practised, the fruits to which they lead are terminable. Mark this well. (And marking this, do thou betake thyself to the path of knowledge).'