You didn’t get this phrasing light/dark cycles from the Bible. You ignore plain reading for made up phrases. I don’t need evidence direct or indirect. I have the scripture which clearly states that there were six days. It would seem that the scriptures go out of the way to make this fact clear by using not only numbers with the word day but also the phrase evening and morning. Again, every other place that the word day is used with evening and morning or with a number it means a literal day. But you are arguing that in this case when it uses BOTH a number and the phrase evening and morning that it only means an unspecified amount of time that has a light/dark cycle.
Mornings and evenings of a “yom” before the Sun had been created? Why that simply HAS to be a 24 hour period. Nothing else could possibly make sense!/s
Do you think perhaps that there might be a deeper meaning, perhaps that God didn't do everything in an instant, but took his time, rolled up HIS metaphorical sleeves, and worked what would be the equivalent of a human being working for six days, and then rested?
The Bible instructs us to pay particular attention to the fact that “a day unto the Lord is as a thousand years, and a thousand years a day.”
And for the thinking impaired, I don't for a ‘yom’ suspect that this poetic language is somehow a direct proportionality.