The Prashna Upanishad with Shankara’s Commentary
प्राणाग्रय एवैतस्मिन्पुरे जाग्रति । गार्हपत्यो ह वा एषो३पानो व्यानोऽन्वाहार्यपचनो यद्गार्हपत्यात्प्रणीयते प्रणयनादाहवनीयः प्राणः ॥ ३ ॥
prāṇāgraya evaitasminpure jāgrati | gārhapatyo ha vā eṣo'pāno vyāno'nvāhāryapacano yadgārhapatyātpraṇīyate praṇayanādāhavanīyaḥ prāṇaḥ || 3 ||
3. The fires of prâna alone wake in this city. This apâna is the gârhapatya fire. Vyâna is the anvâhâryopachana fire. The prâna is the âhavaniya- fire, as it is taken from the gârhapatya fire.
Com.—When the senses, the ear and the rest, are gone to sleep in this city, i.e., in this body of nine apertures, the five winds, prâna and the rest, called fires, being like fire, keep watch. This is their similitude with fires. This apâna is the gârhapatya fire. How is explained; just as, at the time of performing the agnihôtra, another fire named âhavanîya is obtained from the gârhapatya, so from the apâna during sleep, prâna, as it were, the âhavanîya fire is obtained. But Vyâna, emerging from the southern cavity of the heart is called the anvâhâryapachana, or the southern fire, from its connection with the south.