य एनं वेत्ति हन्तारं यश्चैनं मन्यते हतम्। उभौ तौ न विजानीतो नायं हन्ति न हन्यते॥
ya enam vetti hantaram yash chainam manyate hatam ubhau tau na vijanito nayam hanti na hanyate
Translation
He who thinks the soul kills and he who thinks the soul is killed — both are ignorant. The soul neither kills nor is it killed.
Commentary
This verse demolishes Arjuna's core fear. If the soul cannot kill or be killed, then the guilt of killing is based on a fundamental misunderstanding about the nature of reality.