Khandogya-Upanishad: Second Prapathaka, Second Khanda
1. Let a man meditate on the fivefold Saman as the five worlds. The hinkara is the earth, the prastava the fire, the udgitha the sky, the pratihara the sun, the nidhana heaven; so in an ascending line.
2. In a descending line, the hinkara is heaven, the prastava the sun, the udgitha the sky, the pratihara the fire, the nidhana the earth.
3. The worlds in an ascending and in a descending line belong to him who knowing this meditates on the fivefold Saman as the worlds.