Bhagavad Gita 2.26
Even if thou thinkest of it as constantly being born and constantly dying, O Mighty Man, thou still hast no cause to grieve.
अथ चैनं नित्यजातं नित्यं वा मन्यसे मृतम्।
तथापि त्वं महाबाहो नैवं शोचितुमर्हसि॥atha cainaṃ nityajātaṃ nityaṃ vā manyase mṛtam|
tathāpi tvaṃ mahābāho naivaṃ śocitumarhasi||
English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).