Rudrahridaya Upanishad

The text is attached to the Krishna Yajurveda and classified under one of the 14 Shaiva Upanishads.

[4][5] The Upanishad glorifies Shiva and Uma as inseparable, asserts that they together manifest as all gods and goddesses, all animate and inanimate reality of the universe.

[6] This text, like other Shaiva Upanishads, is presented with Vedanta nondualism terminology, and states that the individual Atman (soul) is identical with the supreme reality Brahman.

[3][6] In the Telugu language anthology of 108 Upanishads of the Muktika canon, narrated by Rama to Hanuman, it is listed at number 85.

The text, states Shakya, is the only Upanishad that presents the composite merged form of Rudra-Uma as all truth and reality, and emphasizes this hermaphrodite-style union aspect by presenting the unison in other combinations such as Brahma-Vani and Vishnu-Lakshmi.

[17][18] The text states that the absolute truth is "nirguna (without attributes, abstract), nirakara (without shape), with sensory organs, omnipresent, impersonal, imperishable" and identical to the soul within oneself and each living being.

All reality is the same Shiva and one absolute, which is identical to Om, the Atman, the satcitananda (existence-consciousness-bliss).