Principal Upanishad · Krishna Yajurveda
Shvetashvatara Upanishad 6.11
The one witness, hidden in all beings
एको देवः सर्वभूतेषु गूढः सर्वव्यापी सर्वभूतान्तरात्मा।
The one God, hidden in all beings, all-pervading, the Self within all beings, watching over all works, dwelling in all beings, the witness, the perceiver, the only one, free from qualities.
What this verse points to
A long accumulation of descriptions — hidden, all-pervading, the inner Self of all, the witness, the perceiver — ending on nirguna, free of qualities. The list builds up and then withdraws itself.
"Witness" is the operative word for practice. A witness does not intervene, does not evaluate, and is not altered by what passes in front of it.
Sit with it
Spend a sit deliberately not improving anything. Only witness, and resist the pull to adjust.
About the Shvetashvatara Upanishad
A theistic Upanishad that brings a personal Ishvara into the non-dual framework, and one of the earliest texts to use the word "yoga" in something close to its later technical sense, with practical instruction on posture and breath.
References to this text are given as chapter.verse — here, 6.11.