Bhashya
अपा का गतिरिति, असौ लोक इति होवाच, अमुष्मा-द्धि लोकाद्वृष्टि संभवति ।अमुष्य लोकस्य का गतिरितिपृष्ट दाल्भ्य उवाच-- स्वर्गममु लोकमतीत्य आश्रयान्तरसाम न नयेत्कश्चित् इति होवाच आह ।अतो वयमपिस्वर्गे लोक साम अभिसंस्थापयाम , स्वर्गलोकप्रतिष्ठ सामजानीम इत्यर्थ ।स्वर्गसंस्ताव स्वर्गत्वेन सस्तवन सस्तावोयस्य तत्साम स्वर्गसस्तावम, हि यस्मात् स्वर्गो वै लोकसाम वेद इति श्रुति ॥
In plain words
When asked, 'What is the goal of waters?' he replied, 'That world,' explaining that rain originates from that upper realm. When asked further about the goal of that world, the sage Dālbhya declared: 'Having reached the heavenly world, no one should carry the Sāman further to any other support.' Therefore we too anchor our Sāman in the heavenly world, understanding it to rest securely right there. That whose praise is heaven—having heaven as its laudatory basis—is indeed what is meant, for the Śruti confirms that heaven itself is the Sāman.
Close to the Sanskrit
What is the destination of waters? That world, he said. From that upper world rain originates. What is the destination of that world? Dālbhya, being asked, spoke: Having crossed that heavenly world, no one should lead the Sāman to another support, thus he spoke. Therefore we also establish the Sāman in the heavenly world, we know the Sāman as resting on the heavenly world, this is the meaning. That whose praise is heaven itself—having heaven as its praise—is 'svargasaṃstāva', for indeed the heavenly world knows the Sāman, as the Sruti says.