The Ishvara Gita is an ancient Hindu philosophical text from Kurma Purana.
It follows the oldest Shaiva doctrine of the Vedic mahapashupata school with its scripture Atharvashiras Upanishad and predates the reformed Lakulish pashupata that appeared around 3000 BCE according to the chronology in Vayu Purana.
This is not to be confused with Shiva Gita which is a similar text from the Padma Purana.
The text deals with topics such as Shiva Advaita (Shaiva nondualism) metaphysics, relations Shiva-brahman-Linga, yoga, recitations of om and of the hymn Shatarudriya from Yajurveda, [1] and others [2] The Ishvara Gita consists of 11 chapters with over 768 verses which deals with topics such as worship of the Siva Lingam, Shiva Advaita metaphysics, Omni-Potence of the Śiva-Liṅga,[3] Bhakti, Significance of OM,[4] Theophany of Śiva (śiva-prādurbhāva-ākhya), forms of Shiva (Aṣṭa Mūrtis) and others [2] The Ishvara Gita contains many new themes that are not found in The Bhagavad Gita, such as worship of the Shiva Lingam and the idea of Śiva as the ultimate God.
Several commentaries on this text are available in manuscript form, including one by Vijñānabhikṣu, a 16th-century Hindu polymath.