Verse 1.2.8

यथाश्मानमाखणमृत्वा विध्वंसत एवं हैव स विध्वंसते य एवंविदि पापं कामयते यश्चैनमभिदासति स एषोऽश्माखणः ॥ १.२.८ ॥

yathāśmānamākhaṇamṛtvā vidhvaṃsata evaṃ haiva sa vidhvaṃsate ya evaṃvidi pāpaṃ kāmayate yaścainamabhidāsati sa eṣo'śmākhaṇaḥ || 1.2.8 ||

8. Just as when chunks of earth are thrown against an unbreakable stone they are themselves reduced to dust, similarly, if anyone wishes ill or causes an injury to a person who knows prāṇa, he invites his own destruction thereby. The person who knows prāṇa is immune to injury like a piece of unbreakable stone.

Word-for-word explanation:

Evam yathā, just as [chunks of earth]; ākhaṇam, unbreakable; aśmānam, stone; ṛtvā, having hit; vidhvaṃsate, are smashed; evam ha eva, in the same way; saḥ vidhvaṃsate, a person gets totally destroyed; yaḥ pāpam kāmayate, who wishes ill; evamvidi, of a person who knows thus [the true nature of prāṇa]; yaḥ ca enam abhidāsati, or who causes an injury to such a person; saḥ eṣaḥ, he [who knows] this [prāṇa]; aśmā ākhaṇaḥ, [is like] a stone that can never be broken.

Commentary:

What is the difference between mukhya prāṇa (the chief prāṇa) and the prāṇa that is associated with our breathing, or smelling? Mukhya prāṇa is supreme prāṇa—that is, it is Brahman. It is pure, all-pervasive, and self-sufficient. But our breathing is associated with the organ of smelling and is not independent. It is also not pure. It has limitations and is susceptible to pāpma, impurities—that is, it is sometimes good and sometimes bad. Mukhya prāṇa, however, is always pure, always the same.

One who knows the true nature of prāṇa is immune to injury. And anyone trying to hurt him will end up hurting himself.