Chandogya Upanishad 2.9

Let a man meditate on the sevenfold Sâman as the sun. The sun is Sâman, because he is always the same (sama); he is Sâman because he is the same, everybody thinking he looks towards me, he looks towards me.

Let him know that all beings are dependent on him (the sun). What he is before his rising, that is the hinkâra. On it animals are dependent. Therefore animals say hin (before sunrise), for they share the hinkâra of that Sâman (the sun).

What he is when first risen, that is the prastâva. On it men are dependent. Therefore men love praise (prastuti) and celebrity, for they share the prastâva of that Sâman.

What he is at the time of the sangava, that is the âdi, the first, the Om. On it birds are dependent. Therefore birds fly about in the sky without support, holding themselves, for they share the âdi (the Om) of that Sâman.

What he is just at noon, that is the udgîtha. On it the Devas are dependent (because they are brilliant). Therefore they are the best of all the descendants of Pragâpati, for they share the udgîtha of that Sâman.

What he is after midday and before afternoon, that is the pratihâra. On it all germs are dependent. Therefore these, having been conceived (pratihrita), do not fall, for they share the pratihâra of that Sâman.

What he is after the afternoon and before sunset, that is the upadrava. On it the animals of the forest are dependent. Therefore, when they see a man, they run (upadravanti) to the forest as a safe hiding-place, for they share the upadrava of that Sâman.

What he is when he first sets, that is the nidhana. On it the fathers are dependent Therefore they put them down (nidadhati), for they share the nidhana of that Sâman. Thus a man meditates on the sevenfold Sâman as the sun.