Bhagwad Gita
Chapter 2, Verse 27
जातस्य हि ध्रुवो मृत्युर्ध्रुवं जन्म मृतस्य च।
तस्मादपरिहार्येऽर्थे न त्वं शोचितुमर्हसि।।2.27।।
For one who has taken his birth, death is certain; and for one who is dead, birth is certain. Therefore, in the unavoidable discharge of your duty, you should not lament.