The immortal soul does not reside in only special people.
It is said that every soul residing in a body never dies. This conclusion applies not only to special people or certain beings, but to all bodies.
Here, the first explanation regarding the immortality of the soul, which has been continuing from section 11, is concluded. For anyone, there is no need to lament physical death as the annihilation of the soul. And Krishna tries to return the conversation back to the duty in front of him, away from Arjuna's sadness. The teachings about the soul are not meant to escape reality, but rather to face it correctly.
Japanese Translation from the Geeta Press Edition - Chapter 2, Section 30: "The soul that resides in all bodies is not killed."
In this way, after describing the difficulty and wondrous nature of perceiving, explaining, and listening to the truth about the soul, the Lord concludes his discussion of Samkhya Yoga, which is the yoga of knowledge.
He advises Arjuna that he should not grieve for any being, because the soul is something that can never be truly killed.
Sanskrit original text
देही नित्यमवध्योऽयं देहे सर्वस्य भारत ।
तस्मात्सर्वाणि भूतानि न त्वं शोचितुमर्हसि ॥ ३० ॥Romanization
dehī nityam avadhyo 'yaṃ dehe sarvasya bhārata |
tasmāt sarvāṇi bhūtāni na tvaṃ śocitum arhasi || 30 ||Arjuna, this soul that dwells in all bodies is never destroyed. Therefore, you should not lament for anyone. (30)
"By saying, 'This soul that dwells in every body will never be killed,' the Lord is showing that there is only one soul residing within the bodies of all beings in this world. The diversity of bodies is reflected in the soul due to ignorance. However, in reality, there is no diversity in the soul."
And this ultimate reality, which is the soul, can never be killed. It cannot be destroyed by anyone or by any means.
"Therefore, you should not lament about anyone." In this sentence, the word "therefore" is used to indicate a cause.
This indicates that, in this chapter, it has been clearly shown and proven that the soul is always immortal and that no one has the power to kill it; therefore, Arjuna should not be sad about anyone.
If the soul never ceases to exist and cannot be destroyed by any means, then why should there be a reason for sadness? Therefore, Arjuna should have prepared for battle instead of being consumed by grief.