Valmiki Ramayana Ayodhya Kanda Sarga 77 Shloka 23
Original Shlokaत्रीणि द्वन्द्वानि भूतेषु प्रवृत्तान्यविशेषतः।।2.77.23।। तेषु चापरिहार्येषु नैवं भवितुमर्हसि।
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त्रीणि three, द्वन्द्वानि dualities, भूतेषु in living beings, अविशेषतः without exception, प्रवृत्तानि are applicable, तेषु they, अपरिहार्येषु cannot be eschewed, एवम् भवितुम् to become sorrowful, नार्हसि it does not behove you.
There are three dualities (hunger and thirst, pain and pleasure, birth and death), which are applicable to all living beings without any exception and cannot be eschewed. Therefore, it does not behove you to act in this way.