The three mātrās, when employed separately, are subject to death; united to one another, not separated from each other, employed appropriately in the activities external, internal and intermediate, the knower does not tremble.

This verse contains a warning and a promise:

Warning: The three mātrās employed separately (pravibhaktāḥ) are subject to death (mṛtyu-matyaḥ). One who only meditates on A, or only on AU, attains limited worlds that involve return to mortality.

The key: They must be united (anyonya-saktāḥ), not separated (anaviprayuktāḥ). The complete sound Oṅkāra must be meditated upon as a whole, not as parts.

Employed appropriately (*samyak-prayuktāḥ) in:

• Bāhya — external activities (waking)
• Ābhyantara — internal activities (deep sleep)
• Madhyamā — intermediate activities (dreaming)

The result: Na kampate jñaḥ — “the knower does not tremble.” There is no fear, instability, or doubt. This is abhaya — freedom from fear, one of the attributes of the jīvan-mukta.

For the yogī: the complete Om, meditated in all states of consciousness, leads to absolute stability.