Śivasaṃhitā 3.48

The practice of praṇava (OM) in silence, in a retired place (rahasya), with senses withdrawn (saṃyatendriya) is a mantra japa instruction that complements technical prāṇāyāma. The primordial sound is not pronounced but held internally, becoming pure vibration resonating in the suṣumnā channel. It is the sonic dimension of kumbhaka: not only breath retention but retention of sound in its subtle form.

Praṇava (from prefix pra- + root nu-, to resonate forward) designates the primordial mantra OM as prior to language, the sound that precedes all manifested sounds. Dīrgha praṇava — the long OM — requires that vibration be sustained beyond articulated sound, as an inner resonance that continues after the breath has ceased. This technique is a form of nādānusandhāna, tracking of the subtle internal sound.

The retired place (rahasyasthāna, literally «secret, hidden place») is not only physical privacy: it is the condition of what tantric texts call ekāgratā (single-pointed concentration), impossible in the environment of ordinary social relationships. The instruction situates practice in the liminal space between the public world and the inner silence where OM can do its work.