Text 23
Contents of the Gīā Summarized
103.
the supreme spiritual master—as Arjuna agreed to do by voluntary surrender unto Kṛṣṇa for instruction—the subordinate bird immediately becomes free from all lamentations. Both the  Kaṭha Upaniṣad  and  Śvetāśvatara Upaniṣad  confirm this:
samāne vṛkṣe puruṣo nimagno ’nīśayā śocati muhyamānaḥ juṣṭaṁ yadā paśyaty anyam īśam asya mahimānam iti vīta-śokah
“Although the two birds are in the same tree, the eating bird is fully engrossed with anxiety and moroseness as the enjoyer of the fruits of the tree. But if in some way or other he turns his face to his friend who is the Lord and knows His glories—at once the suffering bird becomes free from all anxieties.” Arjuna has now turned his face towards his eternal friend, Kṛṣṇa, and is understanding the  Bhagavad-gītā  from Him. And thus, hearing from Kṛṣṇa, he can understand the supreme glories of the Lord and be free from lamentation.
Arjuna is advised herewith by the Lord not to lament for the bodily change of his old grandfather and his teacher. He should rather be happy to kill their bodies in the righteous fight so that they may be cleansed at once of all reactions from various bodily activities. One who lays down his life on the sacrificial altar, or in the proper battlefield, is at once cleansed of bodily reactions and promoted to a higher status of life. So there was no cause for Arjuna's lamentation.
TEXT 23
नैनं छिन्दन्ति शस्त्राणि नैनं दहति पावकः । न चैनं क्लेदयन्त्यापो न शोषयति मारुतः ॥ २३ ॥
nainaṁ chindanti śastrāṇi  
 nainaṁ dahati pāvakaḥ  
 na cainaṁ kledayanty āpo  
 na śoṣayati mārutaḥ
na —never;  enam —unto this soul;  chindanti —can cut into pieces;  śastrāṇi —all weapons;  na —never;  enam —unto this soul;  dahati —burns;  pāvakaḥ —fire;  na —never;  ca —also;  enam —unto this soul;  kledayanti —moistens;  āpaḥ —water;  na —never;  śoṣayati —dries;  mārutaḥ —wind.