avinasi tu tad viddhi yena sarvam idam tatam vinasam avyayasyasya na kascit kartum arhati
Translation
Know that which pervades the entire body (i.e soul) is indestructible. No one is capable to destroy this imperishable[soul].
Purport
Bhagvan Shri Krishna explains Arjuna about the truth of soul and body. Bhagvaan says that soul which is the source of life in body can never be destroyed. Nobody can kill soul. Only the material body of the soul is destroyed. Therefore Arjuna should not grieve and fight which is his prescribed duty.
