Bhagavad Gita 2.33
अथ चेत्त्वमिमं धर्म्यं संग्रामं न करिष्यसि । ततः स्वधर्मं कीर्तिं च हित्वा पापमवाप्स्यसि ॥
atha cet tvam imaṃ dharmyaṃ saṅgrāmaṃ na kariṣyasi | tataḥ sva-dharmaṃ kīrtiṃ ca hitvā pāpam avāpsyasi ||
Translation
But if you will not fight this righteous battle, then having abandoned your own duty and fame, you will incur sin.
Reflection
When did sitting it out cost you more than doing it would have?
Read this verse in its chapter: Chapter Two
The reverse case. Refusing the work that is yours has its own cost. Sva-dharmaṃ hitvā. Having abandoned your own duty. Kīrtiṃ hitvā. Having abandoned your fame. Pāpam avāpsyasi. You will incur sin. Krishna names what walking off the field would mean. The verse refuses the framing in which Arjuna's refusal is the safe option. Not doing your duty is itself a cost. The pacifist read of Arjuna's position runs aground here: Krishna does not grant that sitting down is moral neutrality.