Mahanarayana Upanishad is classified as a Vaishnava Upanishad. The text exists in three main versions. One version with 64 chapters is attached to the Krishna Yajurveda in several South Indian anthologies, and the same text in the Andhra edition exists in an expanded form with 80 chapters attached to the same Veda. A second version is attached to the Atharvaveda, has 25 chapters, and is prefixed with Tripadvibhuti.
The text opens with cosmology, with a verse describing the Brahman principle as existent before the creation of the universe, which existed as and in light in the “boundless cosmic water”. The style of its opening verses suggests that the metaphysical principle of Brahman was well established by the time this text was composed. It is described as that where and from which the world originated and into which it shall disintegrate, upon whom all the gods are founded, it is that which was past and what will be, it is all parts of time, it is that which envelops the entire universe, which procreates and is present in all creatures, mobile and immobile, and that which is in Om. It is highest of the highest, greatest of the greatest, it is the law, it is the truth, it is the Brahman. The text calls this metaphysical principle as Agni (fire), Vayu (wind), Surya (sun), Chandrama (moon), Prajapati, Purusha, Rudra, and Narayana, that they are all none other than Brahman.