Bhagavad Gita 11.18
You are imperishable, the only one worthy of being known, the priceless treasure-house of the universe, the immortal guardian of eternal life, and the everlasting spirit.
त्वमक्षरं परमं वेदितव्यं
त्वमस्य विश्वस्य परं निधानम्।
त्वमव्ययः शाश्वतधर्मगोप्ता
सनातनस्त्वं पुरुषो मतो मे॥tvamakṣaraṃ paramaṃ veditavyaṃ
tvamasya viśvasya paraṃ nidhānam|
tvamavyayaḥ śāśvatadharmagoptā
sanātanastvaṃ puruṣo mato me||
English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).