Verse 1.3.3

अथ खलु व्यानमेवोद्गीथमुपासीत यद्वै प्राणिति स प्राणो यदपानिति सोऽपानः । अथ यः प्राणापानयोः संधिः स व्यानो यो व्यानः सा वाक् । तस्मादप्राणन्ननपानन्वाचमभिव्याहरति ॥ १.३.३ ॥

atha khalu vyānamevodgīthamupāsīta yadvai prāṇiti sa prāṇo yadapāniti so'pānaḥ | atha yaḥ prāṇāpānayoḥ saṃdhiḥ sa vyāno yo vyānaḥ sā vāk | tasmādaprāṇannanapānanvācamabhivyāharati || 1.3.3 ||

3. Worship vyāna [the breath held between prāṇa and apāna that enables you to speak] as udgītha. Prāṇa is the breath drawn in and apāna is the breath drawn out. Vyāna is the breath held between prāṇa and apāna. This vyāna is also called vāk [speech], for in speaking a person has to hold the breath.

Word-for-word explanation:

Atha, indirectly; khalu vyānam eva udgītham upāsīta, one should worship vyāna [the bridge between prāṇa (breathing in) and apāna (breathing out)] as udgītha; yat vai prāṇiti, that which is breathed in; saḥ prāṇaḥ, that is prāṇa; yat apāniti, that which is breathed out; saḥ apānaḥ, that is apāna; atha yat prāṇa-apānayoḥ sandhiḥ, then the bridge between prāṇa and apāna; saḥ vyānaḥ, that is vyāna; yaḥ vyānaḥ sā vāk, that which is vyāna is speech; tasmāt, therefore; aprāṇan, without inhaling; anapānan, without exhaling; vācam abhivyāharati, a person speaks.

Commentary:

Here vyāna is being presented for worship as udgītha, for vyāna is only a form of prāṇa. What is vyāna? Vyāna is the bridge between prāṇa and apāna, between breathing in and breathing out. Vyāna is the state in which you hold your breath. Vyāna is also called vāk, speech, for when you speak you have to hold your breath.

Śaṅkara says prāṇa is breathing out and apāna is breathing in. According to Monier-Williams, it is the other way around—prāṇa is breathing in and apāna is breathing out. Macdowell is of the same opinion. Both meanings are correct, depending on the context in which the word is used.