Verse 2.20.1

अग्निर्हिंकारो वायुः प्रस्ताव आदित्य उद्गीथो नक्षत्राणि प्रतिहारश्चन्द्रमा निधनमेतद्राजनं देवतासु प्रोतम् ॥ २.२०.१ ॥

agnirhiṃkāro vāyuḥ prastāva āditya udgītho nakṣatrāṇi pratihāraścandramā nidhanametadrājanaṃ devatāsu protam || 2.20.1 ||

1. Fire is the hiṃkāra, air is the prastāva, the sun is the udgītha, the stars are the pratihāra, and the moon is the nidhana. This Sāma known as Rājana is rooted in the gods and goddesses.

Word-for-word explanation:

Agniḥ hiṃkāraḥ, fire is the hiṃkāra; vāyuḥ prastāvaḥ, air is the prastāva; ādityaḥ udgīthaḥ, the sun is the udgītha; nakṣatrāṇi pratihāraḥ, the stars are the pratihāra; candramāḥ nidhanam, the moon is the nidhana; etat rājanam, this [Sāma called] Rājana; devatāsu protam, is rooted in the gods and goddesses.

Commentary:

In the previous section the Sāma was worshipped in the parts of the body. Now it is being worshipped in the deities—that is, in the forces of nature.

Fire is the first among the forces of nature, so it is the hiṃkāra. Next to the hiṃkāra is the prastāva. Air is called the prastāva because it comes next after fire, and it is also infinite. The sun is the udgītha, for just as the udgītha is the best among the Sāma songs, so also the sun is the best among the forces of nature. The stars lie scattered, and as we locate them it seems that we are ‘collecting’ (pratihāra) them. That is why the stars are said to be the pratihāra. The moon is said to be the nidhana, because active people go to Candraloka, the world of the moon, after death.

The Sāma called Rājana is rooted in the gods and goddesses, for the deities are by nature luminous (rājana).