Verse 2.1.1

॥ द्वितीयोऽध्यायः ॥
समस्तस्य खलु साम्न उपासनं साधु यत्खलु साधु तत्सामेत्याचक्षते यदसाधु तदसामेति ॥ २.१.१ ॥

|| dvitīyo'dhyāyaḥ ||
samastasya khalu sāmna upāsanaṃ sādhu yatkhalu sādhu tatsāmetyācakṣate yadasādhu tadasāmeti || 2.1.1 ||

1. It is good to worship the Sāma with all its parts. All that is good, according to scholars, is called sāma. Similarly, all that is bad is asāma.

Word-for-word explanation:

Samastasya khalu sāmnaḥ upāsanam, the worship of the Sāma as a whole [inclusive of all its parts]; sādhu, [is] good; yat khalu sādhu, whatever is good; tat sāma iti ācakṣate, that is called sāma; yat asādhu, whatever is bad; tat asāma iti, that is asāma.

Commentary:

Much has been said already about the Sāma and the udgītha. And it has also been said that much good follows from their worship. Similarly, the Upaniṣad has discussed the stobhas and shown their importance. So long, the Sāma has been discussed in parts. Now it will be discussed as a whole.

The point of this verse is to emphasize how beautiful it is to worship the Sāma. The Sāma is beautiful and to worship the Sāma is beautiful. The qualifying word used is sādhu. Sādhu means ‘good,’ ‘beautiful,’ ‘chaste,’ ‘elegant,’ and so on. It also means ‘honest,’ ‘morally sound,’ ‘beneficial,’ ‘perfect,’ and ‘above reproach.’ Anything opposed to sādhu is asāma.