When the prāṇa enters brahmarandhra and the mind always remains there, the knower of mudrā truly understands the mudrā through the word of the guru.

This verse describes the final destination of prāṇa and the importance of guidance:

Brahma-randhra-gate prāṇe — when prāṇa enters brahmarandhra.This is the “Brahman hole”, located at the crown of the head, identified with sahasrāra cakra.It is the exit door to transcendence.

Manasi tad-gate sadā — when the mind always remains there.A momentary experience is not enough;establishment (sadā) requires the mind to dwell permanently in that openness.

Mudrā-jña — the knower of mudrās.Who has practiced and understood the mudrās described in Chapter 3.

Vetti mudrāṃ tattvataḥ — understand the mudrā truly, in its essence.There is technical knowledge and essential knowledge;the latter only comes with direct experience.

Guru-vākyena — through the word of the guru.Even with correct practice, complete understanding requires transmission from the teacher.

The Bihar School emphasizes that brahmarandhra represents the culmination of the entire haṭha yoga system.When kuṇḍalinī ascends completely and prāṇa is established in sahasrāra, the final union of Śiva and Śakti takes place.