Dyaúḥ dehí lokám vájrâya viskábhe
Hánâva vṛtrám riṇácâva síndhûn
Índrasya yantu prasavé vísṛshṭâḥ.”
“Friend Vishṇu, stride further,
Dyaus give room for the lightning to leap,
Let us both kill Vṛtra and free the rivers,
Let them go, sent forth at the command of Indra.”
Here, I have little doubt, the ancient Rishis pronounced Dyaû́s, but the later poets, and the still later Âcâryas were satisfied with the acute, and with the acute the word is written here in all the MSS. I know.