ĪŚĀVĀSYOPANIṢAD ｜ ईशावास्योपनिषद्

The Ishavasya Upanishad (or simply Isha) is one of the shortest of its kind, and basically represents a brief philosophical poem discussing the soul/self (Atman). This edition contains the Kanva recension, consisting of 18 verses.

The words “Isha vasyam” literally translates to “enveloped by the Lord” and refers to the theory of soul (Atman); a concept used in both dualism and non-dualism. This book however, including the commentary of Shankara, focuses on non-dualism (advaita).

Source: https://archive.org/details/upanishadssrisan00sita/page/n3/mode/2up?view=theater

https://www.wisdomlib.org/hinduism/book/ishavasya-bhashya-by-sitarama