Bhagavad Gita 2.33
अथ चेत्त्वमिमं धर्म्यं संग्रामं न करिष्यसि। ततः स्वधर्मं कीर्तिं च हित्वा पापमवाप्स्यसि।।2.33।।
atha cettvamimaṃ dharmyaṃ saṃgrāmaṃ na kariṣyasi| tataḥ svadharmaṃ kīrtiṃ ca hitvā pāpamavāpsyasi||2.33||
atha cettvamimam dharmyam samgramam na karishyasi tatah svadharmam kirtim ca hitva papamavapsyasi2.33
Meaning
However, if you refuse to fight this righteous war, you will abandon your duty and honor, and incur sin by failing in your sacred obligation.
परन्तु अगर तू इस धर्मयुक्त युद्ध को नहीं करेगा, तो अपने धर्म और कीर्ति को खोकर पाप को प्राप्त होगा।
This is verse 33 of 72 in Chapter 2 (Sankhya Yoga) of the Bhagavad Gita.