Bhagavad Gita 2.30
देही नित्यमवध्योऽयं देहे सर्वस्य भारत। तस्मात्सर्वाणि भूतानि न त्वं शोचितुमर्हसि।।2.30।।
dehī nityamavadhyo'yaṃ dehe sarvasya bhārata| tasmātsarvāṇi bhūtāni na tvaṃ śocitumarhasi||2.30||
dehi nityamavadhyo'yam dehe sarvasya bharata tasmatsarvani bhutani na tvam shocitumarhasi2.30
Meaning
The soul dwelling in every body is eternally indestructible. Therefore, you should not mourn for any living being, for the true self within them can never be harmed.
हे भारत! सबके शरीर में यह देही (आत्मा) सदा अवध्य है। इसलिए तुझे सभी प्राणियों के लिए शोक नहीं करना चाहिए।
This is verse 30 of 72 in Chapter 2 (Sankhya Yoga) of the Bhagavad Gita.