B.G 2.19

य एनं वेत्ति हन्तारं यश्चैनं मन्यते हतम् । उभौ तौ न विजानीतो नायं हन्ति न हन्यते॥१९ ॥

ya ēnaṁ vētti hantāraṁ yaścainaṁ manyatē hatam। ubhau tau na vijānītō nāyaṁ hanti na hanyatē ॥19॥

[ya = He who; ēnaṁ = this way vētti = thinks; hantāraṁ = the killer; yaścainaṁ = and he who; manyatē = thinks; hatam = as killed;। ubhau = both; tau = they; na vijānītō = don't understand well; nāyaṁ 'nti = neither they get killed; na hanyatē = nor are they killed;]

He who thinks a person to be a killer, and he who thinks another person as killed - both of them are ignorant. He does not kill nor does the other get killed.

Gīta Tātparya 2.19

Jīva is not an independent agent. The above verse is not to show a person does not get killed, as it contradicts with later verse 11.34, which states - “kill those whom I have already killed”.

यः एनं जीवं वेत्ति हन्तारं स्वातन्त्र्येण। अन्यथा ‘मया हतांस्त्वं जहि’ इत्यादिविरोधः । चेतनं प्रति य एनमिति परमात्मनोपि समम् ॥१९॥

yaḥ ēnaṁ jīvaṁ vētti hantāraṁ svātantryēṇa। anyathā ‘mayā hatāṁstvaṁ jahi’ ityādivirōdhaḥ । cētanaṁ prati ya ēnamiti paramātmanōpi samam ॥19॥

G.T 2.19

[yaḥ ēnaṁ jīvaṁ vētti hantāraṁ svātantryēṇa = "He who thinks a person to be a killer" must be interpreted to mean "One who thinks he is an independent agent who kills". anyathā ‘mayā hatāṁstvaṁ jahi' ityādivirōdhaḥ = Otherwise, it contradicts with the statement - ‘Kill those whom I have already killed'(11.34) । cētanaṁ prati = towards the jiva; ya ēnamiti paramātmanōpi samam = as he is similar to Paramatman; ]

One who thinks the person as a killer is ignorant, as he is attributing independent agency to a killer. Interpreting the verse to mean the person does not get killed contradicts the statement–“Kill those whom I have already killed [11.34]”. Ignorant people think that a person can be killed. They fail to understand that Jiva is similar to Paramatman and thus cannot be killed.