The Self as Witness - Sakshi
The Self observes all experience without being affected.
The Sakshi is the pure witness consciousness that observes thoughts, emotions, and perceptions without identification. It is untouched by what it witnesses, like a mirror by reflections.
Just as the sun illumines all without being affected, so the Self illumines all experience.
Recognizing oneself as witness is key to liberation.
Various Upanishads