mam asritya yatanti ye
te brahma tad viduh krtsnam
adhyatmam karma cakhilam
(Knowledge of the Absolute, Text 29 Chapter 7)
Meaning: Intelligent persons who are endeavoring for liberation from old age and death take refuge in Me in devotional service. They are actually Brahman because they entirely know everything about transcendental activities.
*** Birth, death, old age and diseases affect this material body, but not the spiritual body. There is no birth, death, old age and disease for the spiritual body, so one who attains a spiritual body, becomes one of the associates of the Supreme Personality of Godhead and engages in eternal devotional service is really liberated. Aham brahmasmi: I am spirit . It is said that one should understand that he is Brahman, spirit soul. This Brahman conception of life is also in devotional service. The pure devotee are transcendentally situated on the Brahman platform, and they know everything about transcendental activities.
Bhagavad Gita: Intelligent persons take refuge in Me in devotional service [Knowledge of the Absolute (Text 29 Chapter 7)]