Chapter 2 · The Yoga of Knowledge · Krishna said
Bhagavad Gita 2.26 — Even then, do not 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 ||
Meaning
And even if you think the soul is always being born and always dying, mighty Arjuna, you still should not grieve.