Verse 1.3.2

समान उ एवायं चासौ चोष्णोऽयमुष्णोऽसौ स्वर इतीममाचक्षते स्वर इति प्रत्यास्वर इत्यमुं तस्माद्वा एतमिमममुं चोद्गीथमुपासीत ॥ १.३.२ ॥

samāna u evāyaṃ cāsau coṣṇo'yamuṣṇo'sau svara itīmamācakṣate svara iti pratyāsvara ityamuṃ tasmādvā etamimamamuṃ codgīthamupāsīta || 1.3.2 ||

2. This prāṇa and that sun are alike. Prāṇa is warm, and the sun is also warm. Prāṇa is called svara [when it is ‘going out’ at the time of death]. The sun is also described as svara [when it ‘sets’] and pratyāsvara [when it ‘comes back’]. Therefore, worship both prāṇa and the sun as udgītha.

Word-for-word explanation:

Ayam, this [prāṇa]; ca asau, and that [sun]; samānaḥ eva, are equivalent; u ayam, this [prāṇa]; uṣṇaḥ, is warm; ca asau, and that [sun]; uṣṇaḥ, is warm; imam, this [prāṇa]; svaraḥ iti ācakṣate, [sages] call it svara [‘outgoing,’ at the time of death]; amum, that [sun]; svaraḥ iti, has set; pratyāsvaraḥ iti, [and] has returned [this is what people say]; tasmāt vai, for that reason; etam, this [going out]; imam, this [prāṇa]; ca amum, and that [sun]; udgītham upāsīta, worship as udgītha.

Commentary:

Prāṇa and āditya (the sun) are similar. Both are warm. Sages call both svara, which means ‘going out.’ The difference is that while prāṇa goes out (at the time of death), the sun goes out (when it sets) and also returns (pratyāsvara, when it rises). Thus, prāṇa and āditya are similar in name and quality.

It is therefore appropriate to worship both as udgītha. Both are Om.