Mbh 12.61.1a

"'Bhishma said, "O mighty-armed one, listen now to me, O thou of prowess incapable of being baffled, as I mention the names of the four modes of life and the duties in respect of each. The four modes are Vanaprastha, Bhaikshya, Garhasthya of great merit, and Brahmacharya which is adopted by Brahmanas. Undergoing the purificatory rite in respect of bearing matted locks, after having gone through the rite of regeneration and performed for some time the rites in respect of the sacred fire and studied the Vedas, one should, with cleansed soul and senses under restraint, having first carefully performed all the duties of the mode called Garhasthya, proceed, with or without his wife, to the woods for adoption of the mode called Vanaprastha. Having studied the scriptures called Aranyakas, having drawn up his vital fluid and having retired from all worldly affairs, the virtuous recluse may then attain to an absorption with the eternal Soul knowing no decay. These are the indications of Munis that have drawn up their vital fluid. A learned Brahmana, O king, should first practise and perform them. The Brahmana, O king, that is desirous of emancipation, it is well known, is competent to adopt the Bhaikshya mode after having gone through the mode called Brahmacharya. Sleeping at that place (in the course of the wanderings) where evening overtakes him, without desire of bettering his situation, without a home, subsisting on whatever food is obtained (in charity), given to contemplation, practising self-restraint, with the senses under control, without desire, regarding all creatures equally, without enjoyments, without dislike to anything, the Brahmana possessed of learning, by adopting this mode of life, attains to absorption with the eternal Soul that knows no decay. The person leading the Garhasthya mode of life should, after studying the Vedas, accomplish all the religious acts laid down for him. He should beget children and enjoy pleasures and comforts.