This earth is the Rik and fire is the Saman. This Saman (i.e. fire) rests on that Rik (i.e. the earth). Therefore the Saman is sung resting on the Rik. Sa is the earth, ama is fire; thus they (the earth and fire) are designated as Sama.

Sama Veda, Chandogya Upanishad I, VI - The Luminous Person in the Solar Orb, 1

The mid-region is the Rik and the air is the Saman. This Saman (i.e. the air) rests on that Rik (i.e. the mid-region). Therefore the Saman is sung, resting on the Rik. Sa is the mid-region, ama is the air; thus they (the mid-region and the air) are designated as Sama.

Sama Veda, Chandogya Upanishad I, VI - The Luminous Person in the Solar Orb, 2

The stars are the Rik and the moon is the Saman. This Saman (i.e. the moon) rests on that Rik (i.e. the stars). Therefore the Saman is sung, resting on the Rik. Sa is the stars, ama is the moon; thus they (the stars and the moon) are designated as Sama.

Sama Veda, Chandogya Upanishad I, VI - The Luminous Person in the Solar Orb, 4

Now, the white radiance of the sun is the Rik and its blue intense darkness is the Saman. This Saman (i.e. the darkness) rests on that Rik (i.e. the radiance). Therefore the Saman is sung, resting on the Rik.

Sama Veda, Chandogya Upanishad I, VI - The Luminous Person in the Solar Orb, 5

Sa is the white radiance of the sun, ama is its blue intense darkness; thus they (the radiance and the darkness) are designated as Sama. Now, the golden person who is seen in the sun, who has a golden beard and golden hair, who is golden to the very tips of his nails-his eyes are like a lotus flower, red as the rump of a monkey. His name is Ut, for he has risen (udita) above all evil. He, too, who knows this rises above all evil.

Sama Veda, Chandogya Upanishad I, VI - The Luminous Person in the Solar Orb, 6-7