Shrimad Bhagwat Gita
The soul is neither born, nor does it ever die; nor having once existed, does it ever cease to be. The soul is unborn, eternal, immortal, and primeval. It is not destroyed when the body ceases to exist.
O son of Kunti, the transactional presence of happiness and distress, and their absence at another time, is like the appearance and disappearance of winter and summer seasons. These perceptions are transient, and arise from an interaction between the senses and the world around us. O descendent of Bharat, one must learn to tolerate them without feeling disturbed.
Just as the embodied soul continuously passes from childhood to youth to old age, similarly, at the time of death, the soul passes into another body. Those who are wise are not mystified by this transition.
Never was there a time when I did not exist, nor you, nor all these kings; nor in the future shall any of us cease to be.
I am confused about my duty, and am enveloped with anxiety. I have lost my composure. I am your disciple, and my soul is surrendered to you. Please instruct me and show me the way.
You speak words of wisdom, but you are mourning for that which is not worthy of grief. Those who are wise lament neither for the living nor for the dead.
Dhritarashtra said: O Sanjay, after gathering on the holy field of Kurukshetra, and desirous to fight, what did my sons and the sons of Pandu do?