Question

what is upanishads name three of them

Answer 1

each of a series of Hindu sacred treatises written in Sanskrit c. 800–200 BC, expounding the Vedas in predominantly mystical and monistic terms.
eg)Īśā (IsUp), Yajurveda.Kena (KeUp), Samaveda.Kaṭha (KaUp), Yajurveda.

Answer 2

The Upanishads, a part of the Vedas, are ancient Sanskrit texts that contain some of the central philosophical concepts and ideas of Hinduism, some of which are shared with Buddhism, Jainism, and Sikhism.