verse 33

अथ चेतत्त्वमिमं धर्म्यं संग्रामं न करिष्यसि |
तत: स्वधर्मं कीर्तिं च हित्वा पापमवाप्स्यसि || 33||

Now if thou wouldst not fight this lawful battle, then, having
abandoned thine own duty and fame, thou shalt incur sin.

Arjuna needs to perform his duty as warrior when opportunity
arises. If he does not do his duty (swadharma) he will surely
lose his good reputation and incur sin.