The Bhagavad Gita, which means, “The Song of God”, often referred to as the Gita, is a 700-verse Hindu scripture that is part of the epic Mahabharata.
The Bhagavad Gita is the best known and most famous of Hindu texts, with a unique pan-Hindu influence.
The Gita’s call for selfless action inspired many leaders of the Indian independence movement including Bal Gangadhar Tilak and Mahatma Gandhi; the latter referred to it as his “spiritual dictionary“.
Krishna speaking to Arjuna:
II.19. He who takes the Self to be the slayer and he who thinks It is slain, neither of them KNOWS. It slays not, nor is It slain.
COMMENTARY: The Self is non-doer (Akarta) and as It is immutable, it is neither the agent nor the object of the act of slaying. He who thinks “I slay” or “I am slain” with the body or the Ahamkara (ego), he does not really comprehend the true nature of the Self. The Self is indestructible.
It exists in the three periods of time. It is Sat (Existence). When the body is destroyed, the Self is not destroyed. The body has to undergo change in any case. It is inevitable. But the Self is not at all affected by it. Verses 19, 20, 21, 23 and 24 speak of the immortality of the Self or Atman.
Commentary by Swami Sivananda