SB 11.18: Description of Varṇāśrama-dharma
As related in this chapter, Lord Śrī Kṛṣṇa explained to Uddhava the duties of the vānaprastha and sannyāsa orders and the religious practices proper to each of these levels of advancement.
One who is taking to the vānaprastha stage of life should leave his wife at home in the care of his sons, or else take her along, and with a peaceful mind spend the third quarter of his life in the forest. He should accept as his food whatever bulbs, fruits, roots and so on that grow in the forest, taking sometimes grains cooked by fire and sometimes fruits ripened by time. Furthermore, he should take as his garments tree bark, grass, leaves or the skin of a deer. It is prescribed that he should perform austerities by not cutting his hair, beard, or nails. Nor should he make any special attempt to remove dirt from his limbs. He should bathe three times daily in cold water and sleep upon the ground. During the hot season he should stand beneath the fearsome heat of the sun with fires blazing on four sides. During the rainy season he should stand in the midst of the downpour of rain, and during the cold winter he should submerge himself in water up to his neck. He is absolutely forbidden to clean his teeth, to store food that he has collected at one time to eat at another time, and to worship the Supreme Lord with the flesh of animals. If he can maintain those severe practices for the remainder of his life, the vānaprastha will achieve the Tapoloka planet.
The fourth quarter of life is meant for sannyāsa. One should develop complete detachment from attaining residence on different planets, up to even Brahmaloka. Such wishes for material elevation are due to desire for the fruits of material activity. When one recognizes that endeavors to achieve residence on the higher planets ultimately award only suffering, then it is enjoined that one should take to sannyāsa in a spirit of renunciation. The process of accepting sannyāsa involves worshiping the Lord with sacrifice, giving everything one possesses in charity to the priests and establishing within one’s own heart the various sacrificial fires. For a sannyāsī, association with women or even the sight of women is more undesirable than taking poison. Except in emergencies, the sannyāsī should never wear more clothing than a loincloth or some simple covering over his loincloth. He should carry no more than his staff and waterpot. Giving up all violence to living creatures, he should become subdued in the functions of his body, mind and speech. He should remain detached and fixed on the self and travel alone to such pure places as the mountains, rivers and forests. Thus engaged, he should remember the Supreme Personality of Godhead and dwell in a place that is fearless and not heavily populated. He should take his alms each day at seven homes chosen at random from those of the members of the four social classes, avoiding only the homes of those who are cursed or fallen. With a pure heart he should offer to the Supreme Personality of Godhead whatever food he has collected and take the mahā-prasādam remnants. In this way he should always be mindful that hankering for sense gratification is bondage and that engaging the objects of the senses in the service of Lord Mādhava is liberation. If one lacks knowledge and renunciation, or continues to be troubled by the unconquered six enemies headed by lust and the all-powerful senses, or if one accepts the tridaṇḍa renounced order simply for the purpose of carrying out a livelihood, then he will achieve as his result only the killing of his own soul.
A paramahaṁsa is not under the control of injunctions and prohibitions. He is a devotee of the Supreme Lord, detached from external sense gratification and completely free from desire for even such subtle gratificatory goals as liberation. He is expert in discrimination and, just like a simple child, is free from concepts of pride and insult. Although actually competent, he wanders about like a dull person, and although most learned, he engages himself like an insane fool in incoherent speech. Although actually fixed in the Vedas, he behaves in an unordered fashion. He tolerates the evil words of others and never shows contempt for anyone else. He avoids acting as an enemy or vainly indulging in argument. He sees the Supreme Personality of Godhead in all creatures and also all living beings within the Supreme Personality of Godhead. In order to keep his body alive for performing worship of the Lord, he accepts whatever excellent or inferior food, clothing and bedding he can obtain without endeavor. Although he has to make some effort to find food for maintaining his body, he does not become joyful when he finds something, nor does he become depressed when not finding anything. The Supreme Lord Himself, although not at all subject to the Vedic orders and prohibitions, by His own free will executes various prescribed duties; similarly the paramahaṁsa, even while on the platform of freedom from subjugation to Vedic rules and prohibitions, carries out various duties. Because his perception of dualities has become completely eradicated by transcendental knowledge, which is focused on the Supreme Lord, he obtains upon the demise of his material body the liberation known as sārṣṭi, in which one becomes equal in opulence with the Lord.
The person who desires his own best interest should take shelter of a bona fide spiritual master. Filling his mind with faith, keeping free from enviousness and remaining fixed in devotion, the disciple should serve the spiritual master, whom he should regard as nondifferent from the Supreme Lord. For a brahmacārī, the primary duty is service to the spiritual master. The main duties for a householder are protection of living beings and sacrifice, for a vānaprastha austerities, and for a sannyāsī self-control and nonviolence. Celibacy (practiced by householders at all times except once a month when the wife is fertile), penance, cleanliness, self-satisfaction, friendship with all living beings and above all worship of the Supreme Personality of Godhead are duties meant for every jīva soul. One acquires firm devotion for the Supreme Lord by always rendering service to the Supreme Personality of Godhead through one’s own particular prescribed duty, by not engaging in the worship of any other personalities, and also by thinking of all creatures as the place of residence of the Supreme Personality of Godhead in His form as the Supersoul. The followers of the karma-kāṇḍa section of the Vedas can attain the planets of the forefathers and so on by their ritualistic activities, but if they become endowed with devotion for the Supreme Lord, then by these same activities they can achieve the supreme stage of liberation.