अनात्मनामहंकारादीनां येनानुभुयते ।
साक्षी तदात्मज्ञानं स्याद्येनैवाम्रतमस्यते ॥ ३ ॥
That which experiences the non-Self, egotism etc.
As the Witness, that is Self-wisdom, from which even non-death is obtained.
Commentary
What experiences the non-Self, egotism, etc. is the witnessing Self, untouched by whatever pertains to the non-Self. Sankaracharya points out in the Atmabodha (verse 17) that it is the Self which is the witness of the body, senses, etc.
Here the sage tells us that non-death is obtained from Self-wisdom, which shows that the non-Self, egotism, etc. are perishable. The relative is death-like, and when the relative is put away what remains is non-death. The Brihadaranyaka Upanishad (IV. 4.14) confirms this: "They who know this (Self) attain non-death, while others only go to sorrow."