The Brihadaranyaka Upanishad (Sanskrit: बृहदारण्यकोपनिषद्, IAST: Bṛhadāraṇyakopaniṣad) is one of the Principal Upanishads and one of the first Upanishadic scriptures of Hinduism. A key scripture to various schools of Hinduism, the Brihadaranyaka Upanishad is tenth in the Muktikā or "canon of 108 Upanishads".
The Brihadaranyaka Upanishad is estimated to have been composed about 7th–6th century BCE, excluding some parts estimated to have been composed after the Chandogya Upanishad. The Sanskrit language text is contained within the Shatapatha Brahmana, which is itself a part of the Shukla Yajur Veda.The Brihadaranyaka Upanishad is a treatise on Ātman (Self), includes passages on metaphysics, ethics, and a yearning for knowledge that influenced various Indian religions, ancient and medieval scholars, and attracted secondary works such as those by Adi Shankara and Madhvacharya.