Dhutanga
Dhutanga (Pali "dhutaṅga," ) or dhūtaguṇa (Sanskrit) is a group of austerities or ascetic practices taught in Buddhism. The Theravada tradition teaches a set of thirteen dhutangas, while Mahayana Buddhist sources teach a set of twelve dhūtaguṇas. The term is generally understood to be derived from the root "dhu" "to shake" and could mean practices which help one "shake off" the defilements. Thus, the dhutangas are meant help eliminate the defilements in the mind, and thus to deepen Buddhist practice. Their aim is to help the practitioner to develop detachment with material things including the body. Dhutanga practice is not  considered a necessary requirement for a monk as is Śīla (virtue). Theravada Buddhism. As these thirteen ascetic practices are mentioned in the Pali Tipitaka merely by its name, the "Visuddhimagga" is considered the only place in the Theravada Literature where adequate descriptions on dhutangas are found. The "Visuddhimagga", the central Theravada Buddhist commentary treatise, by highly revered 5th century monk Buddhaghosa Thera, sets out detailed practical instructions for developing purification of mind by devoting a whole chapter to discussing dhutangas. The thirteen dhutangas. The "Visuddhimagga" lists the practices as follows: Thirteen kinds of ascetic practices have been allowed by the  Blessed One to clansmen who have given up the things of the flesh and, regardless of body and life, are desirous of undertaking a practice in conformity [with their aim]. They are: Benefits. Benefits of forest-dwelling practice, as mentioned in Visuddhimagga:The benefits are these. A forest-dwelling bhikkhu who has given attention to the perception of forest (see MN 121) can obtain hitherto unobtained concentration, or preserve that already obtained. And the Master is pleased with him, according as it is said: “So, Nágita, I am pleased with that bhikkhu’s dwelling in the forest” (A III 343 ). And when he lives in a remote abode his mind is not distracted by unsuitable visible objects, and so on. He is free from anxiety; he abandons attachment to life; he enjoys the taste of the bliss of seclusion, and the state of the refuse-rag wearer, etc., becomes him. 55. He lives secluded and apart, Remote abodes delight his heart; The Saviour of the world, besides, He gladdens that in groves abides. The hermit that in woods can dwell Alone, may gain the bliss as well Whose savour is beyond the price Of royal bliss in paradise. Wearing the  robe of rags he may Go forth into the forest fray; Such is his mail, for weapons too The other practices will do. One so equipped can be assured Of routing Mára and his horde. So let the forest glades delight A wise man for his dwelling’s site. In Mahayana sources. Mahayana sources like the "Samadhirajasūtra", the "Daśabhūmikasūtra" and Shantideva teach and promote the practice of twelve dhūtaguṇas as important elements of the bodhisattva path. The "Dharma-saṃgraha" lists the following: The "Samadhirajasūtra" lists the advantages that one gains from practicing the dhūtaguṇas:He is free from "deceit and  loquacity (or from deceitful talk). He does not exalt himself; and he does not revile (or decry) others. He moves about in the houses (of the laity) without undue friendliness or repugnance. He preaches the Doctrine (literally, "bestows the gift of the dharma") in a disinterested spirit. His religious teaching is effective. Notable Early Practitioners. Mahākassapa Thera. Mahākassapa was one of the most revered of the Buddha's disciples, the renunciant par excellence. He was praised by the Buddha as foremost in ascetic practices (Pali: "dhutavādānaṃ") and a foremost forest dweller. Mahākassapa Thera took upon him the thirteen ascetic practices  (including living in the wilderness, living only from alms and wearing rag-robes) and became an enlightened disciple ("arahat") in nine days. He excelled in supernatural accomplishments (Pali: "iddhi"; Sanskrit: "ṛddhi") and was equal to the Buddha in meditative absorption (Pali: "jhāna"; Sanskrit: "dyāna"). He is depicted as a monk with great capacity to tolerate discomfort and contentment with the bare necessities of life. It is said that Mahākassapa assumed leadership of the monastic community following the "paranibbāṇa" (death) of the Buddha. And in many post-canonical texts, Mahākassapa decided at the end of his life to enter a state  of meditation and suspended animation, which was believed to cause his physical remains to stay intact in a cave under a mountain called Kukkuṭapāda, until the coming of Metteyya Buddha.