Vishnupurana 3.9.23

3.9.23

yastvetāṃ niyataścaryāṃ vānaprasthaścarenmuniḥ /
sa dahatyagnivaddoṣāñjayellokāṃś ca śāśvatān //

"When the householder, after performing the acts incumbent on his condition, arrives at the decline of life, let him consign his wife to the care of his sons, and go himself to the forests. Let him there subsist upon leaves, roots, and fruit; and suffer his hair and beard to grow, and braid the former upon his brows; and sleep upon the ground: his dress must be made of skin or of Káśa or Kuśa grasses; and he must bathe thrice a day; and he must offer oblations to the gods and to fire, and treat all that come to him with hospitality: he must beg alms, and present food to all creatures: he must anoint himself with such unguents as the woods afford; and in his devotional exercises he must be endurant of heat and cold. The sage who diligently follows these rules, and leads the life of the hermit (or Vánaprastha), consumes, like fire, all imperfections, and conquers for himself the mansions of eternity.