Verse 1.4.5

स य एतदेवं विद्वानक्षरं प्रणौत्येतदेवाक्षरं स्वरममृतमभयं प्रविशति तत्प्रविश्य यदमृता देवास्तदमृतो भवति ॥ १.४.५ ॥
॥ इति चतुर्थः खण्डः ॥

sa ya etadevaṃ vidvānakṣaraṃ praṇautyetadevākṣaraṃ svaramamṛtamabhayaṃ praviśati tatpraviśya yadamṛtā devāstadamṛto bhavati || 1.4.5 ||
|| iti caturthaḥ khaṇḍaḥ ||

5. Even now anyone who knows this Om and worships it thus can attain the fearlessness and immortality of Om, which is akṣara, or svara. By becoming one with Om, a person can attain immortality, just as the gods and goddesses did.

Word-for-word explanation:

Saḥ yaḥ, one who; evam etat akṣaram vidvān praṇauti, knows this akṣara and respects it as such; etat eva svaram, that known as svara; amṛtam abhayam akṣaram praviśati, becomes one with the immortal and fearless akṣara [Om]; tat, that [akṣara]; praviśya, having become one with [akṣara]; devāḥ yat amṛtāḥ, by which the gods and goddesses became immortal; tat amṛtaḥ bhavati, that person also becomes immortal. Iti caturthaḥ khaṇḍaḥ, here ends the fourth section.

Commentary:

By worshipping svara (Om), the gods and goddesses entered into svara, which means they became one with it. And by becoming one with it, they became fearless and immortal. The same thing may happen to anyone who follows in their footsteps—that is, anyone who worships svara. The transformation is the same as in the case of the gods and goddesses—no more, no less.