Mbh 1.147.4

“And after the citizens had ceased following the Pandavas, Vidura, conversant with all the dictates of morality, desirous of awakening the eldest of the Pandavas (to a sense of his dangers), addressed him in these words. The learned Vidura, conversant with the jargon (of the Mlechchhas), addressed the learned Yudhishthira who also was conversant with the same jargon, in the words of the Mlechchha tongue, so as to be unintelligible to all except Yudhishthira. He said, ‘He that knoweth the schemes his foes contrive in accordance with the dictates of political science, should, knowing them, act in such a way as to avoid all danger. He that knoweth that there are sharp weapons capable of cutting the body though not made of steel, and understandeth also the means of warding them off, can never be injured by foes. He liveth who protecteth himself by the knowledge that neither the consumer of straw and wood nor the drier of the dew burneth the inmates of a hole in the deep woods. The blind man seeth not his way: the blind man hath no knowledge of direction. He that hath no firmness never acquireth prosperity. Remembering this, be upon your guard. The man who taketh a weapon not made of steel (i.e., an inflammable abode) given him by his foes, can escape from fire by making his abode like unto that of a jackal (having many outlets). By wandering a man may acquire the knowledge of ways, and by the stars he can ascertain the direction, and he that keepeth his five (senses) under control can never be oppressed y his enemies.’