हन्ता चेन्मन्यते हन्तुँ हतश्चेन्मन्यते हतं ।
उभौ तौ न विजानीतो नायँ हन्ति न हन्यते ॥ १९ ॥

hantā cenmanyate hantum̐ hataścenmanyate hataṃ ।
ubhau tau na vijānīto nāyam̐ hanti na hanyate ॥ 19 ॥

19. The slayer who thinks of slaying this and the slain who thinks this slain, both these do not know. This slays not, nor is slain.

Shankara’s Commentary:

Even the atman of such description, the slayer who sees the mere body as the atman thinks of slaying and he who thinks that his atman is slain, both these do not know their own atman; for, he does not slay the atman, being incapable of modification; nor is he slain being incapable of modification like the akas. Therefore, all samsara, the fruit of virtue and vice is only in the case of those who do not know the atman, and not in the case of one who knows the Brahman; for in his case, virtue and vice are inappropriate both from the authority of the srutis and from the cogency of reasoning.