Gopala Tapini Upanishad
Gopāla-tāpanī Upanishad is a Sanskrit text, probably composed in the first half of 2nd-millennium CE, and a minor Upanishad attached to the Atharvaveda. The Gopāla-tāpanī is one of the four Tāpinī Upanishads (Nṛsiṁha, Rāma, Tripurā and Gopāla).
The central character of the text is Radha who is described as the Shakti of Krishna, her devotion and discussion of Gopala Krishna. Gopala Krishna is presented as identical to the nondual Absolute Reality (Atman-Brahman), the sat-cit-ananda, the Guru, the Om and the object of Vedanta, who can be reached by devotion to love. It is an important text to the Vaiṣṇava schools of Hinduism, particularly the Gaudiya Vaishnavas of Bengal region of South Asia.
The text is listed as 95th in the Telugu language Muktika anthology of 108 Upanishads.
Farquhar dates it to have been composed after Nṛsiṁha-tāpanī Upanishad, which he estimates to be complete by the 7th century. He states that the first of the Tāpanīya Upanishads is believed to be the Nṛsiṁha, which served as the model for the others which took this name. The Gopalatapani text was extensively commented by the 16th-century scholar Jiva Goswami placing the two limits on its composition century. The 14th-century scholar Vidyaranya commented on Tapani series of Upanishad, so it is possible the text existed by then.
The Sanskrit word tāpanīya in the context of these Upanishads is not clear. The word is found in four different forms: tapanīya, tāpanīya, tāpinī, tāpanī. Tāpanī is the most common form used in titles and references, but this appears to be an abbreviated form of the more correct tāpanīya, which appears in the texts themselves. According to Monier-Williams verdict we should assume tāpanīya ("gold") to be the name of a school of the Vājaseyani Saṁhitā that produced the four Upanishads bearing this name. This assumes that they come from a common source something disputed by others, who believe that the three other works were written on the model of the Nṛsiṁha-tāpanī as a result of the success enjoyed by that work in bringing legitimation a particular ancient tradition containing Nṛsiṁha mantra. Deussen reads tapanīya, which means "that which must be heated" or "gold". It also has the meaning of "self-mortification".
The process of self-purification is often compared to smelting gold, which is heated repeatedly in fire to remove any impurities. Deussen thus explains the term is as follows: "Tapanam (austerity) is burning pain-suffering or ascetic self-sacrifice; Nṛsiṁha-tapanam thus means ascetic self-surrender to Nṛsiṁha. Therefore Nṛsiṁha-tapanīya Upanishad is "the doctrine concerning the ascetic surrender to Nṛsiṁha."