Atharvaveda 3.13

Since formerly (? adás), going forth together, ye resounded (nad) when the dragon was slain, thenceforth ye are streams (nadī́) by name: these are your names, O rivers.

When, sent forth by Varuna, ye thereupon (ā́t) quickly skipped (valg) together, then Indra obtained (āp) you as ye went; therefore are ye waters (ā́p) afterward.

As ye were flowing perversely (apakāmám), since Indra verily hindered (var) you by his powers, you, ye divine ones, therefore the name water (vā́r) is assigned you.

The one god stood up to you, flowing at [your] will; "the great ones have breathed up (ud-an)," said he; therefore water (udaká) is [so] called.

The waters [are] excellent; the waters verily were ghee; these waters verily bear Agni-and-Soma; may the strong (tīvrá) satisfying savor (rása) of the honey-mixed (-pṛc) come to me along with breath, with splendor.

Then indeed I see, or also hear; unto me comes the noise, to me the voice of them; I think myself then to have partaken ambrosia (amṛ́ta) when, ye gold-colored ones, I have enjoyed (tṛp) you.

This, O waters, [is] your heart, this your young (vatsá), ye righteous ones; come thus hither, ye mighty ones, where I now make you enter.