Bhagavad Gita 2.28

The end and beginning of beings are unknown; we only see the intervening formations. So, what is there to grieve about?

अव्यक्तादीनि भूतानि व्यक्तमध्यानि भारत।
अव्यक्तनिधनान्येव तत्र का परिदेवना॥

avyaktādīni bhūtāni vyaktamadhyāni bhārata|
avyaktanidhanānyeva tatra kā paridevanā||

English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).