Dhutanga (Pali dhutaṅga, Sinhala: ධුතාඞ්ග) or dhūtaguṇa (Sanskrit) is a group of austerities or ascetic practices taught in 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.
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.
So let the forest glades delight A wise man for his dwelling’s site.Mahayana sources like the Samadhirajasūtra, the Daśabhūmikasūtra and Shantideva teach and promote the practice of twelve dhūtaguṇas as important elements of the bodhisattva path.
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.