Verse 2.2.1

लोकेषु पञ्चविधं सामोपासीत पृथिवी हिंकारः । अग्निः प्रस्तावोऽन्तरिक्षमुद्गीथ आदित्यः प्रतिहारो द्यौर्निधनमित्यूर्ध्वेषु ॥ २.२.१ ॥

lokeṣu pañcavidhaṃ sāmopāsīta pṛthivī hiṃkāraḥ | agniḥ prastāvo'ntarikṣamudgītha ādityaḥ pratihāro dyaurnidhanamityūrdhveṣu || 2.2.1 ||

1. One should worship the Sāma in a fivefold manner, treating the different parts as symbols of the worlds.

Word-for-word explanation:

Pañcavidham sāma upāsīta, one should worship the Sāma in a fivefold manner; lokeṣu, as the worlds [such as the earth]; hiṃkāraḥ, [for instance, thinking of] the syllable hiṃ; pṛthivī, [as] the earth; prastāvaḥ agniḥ, the prastāva as fire; udgīthaḥ antarikṣam, the udgītha as the sky; pratihāraḥ ādityaḥ, the pratihāra as the sun; nidhanam dyauḥ, the nidhana as heaven; ūrdhveṣu iti, which is up above.

Commentary:

What is the meaning of sādhu? It may mean either dharma or Brahman. Both, however, mean the same thing, more or less. Those who worship Sāma should know that they are worshipping either of these two, and that they are worshipping something uplifting, something propitious (sādhu). When a person worships thus, he becomes what he is worshipping. He becomes a new person altogether. He is totally transformed.

But where is a person to find the Sāma? This Sāma is everywhere, in everything—in the earth, in fire, in the sky, in the sun, and in heaven. But since you cannot approach all of these, you can worship them through their symbols. In this verse, five symbols have been mentioned, which can be used for worship: hiṃkāra, prastāva, udgītha, pratihāra, and nidhana. This fivefold worship of Sāma is being recommended here for everyone.