It is one of the 31 Upanishads attached with  Atharvaveda and classified as one of the Vaishnava Upanishads. It is presented in two parts, the Purva Tapaniya Upanishad and the Uttara Tapaniya Upanishad, which formed the main scriptures of the Nrisimha sect of the Vaishnavas. The text is notable for asserting a fourfold identity, that Atman (soul, self) is the same as Om, Brahman  (Absolute Reality), and Vishnu man-lion avatar Nrisimha. The Upanishad opens with verses of the Rigveda. Its foundation of monism philosophy, as well its style is also found in other Vaishnava Upanishads such as those dedicated to Rama. The  Nrisimha Mantra, with its four supplementary mantras, is enunciated with the epithet “mantra raja” (king of hymns). It has “Om” as the foremost hymn which is repeatedly emphasized throughout this Upanishad. The text discusses Nrisimha Mantra and related hymns.