Bhagavad Gita 2.26
अथ चैनं नित्यजातं नित्यं वा मन्यसे मृतम्। तथापि त्वं महाबाहो नैवं शोचितुमर्हसि।।2.26।।
atha cainaṃ nityajātaṃ nityaṃ vā manyase mṛtam| tathāpi tvaṃ mahābāho naivaṃ śocitumarhasi||2.26||
atha cainam nityajatam nityam va manyase mritam tathapi tvam mahabaho naivam shocitumarhasi2.26
Meaning
Even if you believe the soul is perpetually born and perpetually dies, you still have no reason to grieve, for death is certain for the born, and rebirth is certain for the dead.
यदि तू इसे नित्य जन्म लेने वाला और नित्य मरने वाला मानता है, तो भी हे महाबाहो! इस प्रकार शोक करना उचित नहीं।
This is verse 26 of 72 in Chapter 2 (Sankhya Yoga) of the Bhagavad Gita.