Or HaChaim on Genesis 1:16/אור החיים על בראשית א׳:ט״ז

1And God made, etc.: And the reason that it did not suffice with that which it said earlier, "and it was so" upon all that is stated, is because the [act] here is a new act. Since, after the moon was reduced - as it is stated in their words (Chullin 60b) - God refined and fixed a new act [of creation]; since He fixed the rule of the moon by night - as it does not have rulership during the day in front of the light of the sun - and had the stars accompany it. And this is not in contradiction to that which God stated in the beginning of his words, since he already hinted to the end of [His] word at its beginning, as I [showed] by being precise, in its stating, "let there be" (in the singular to show that only one luminary would be great). And even if we explained it in a different way, [the text] supports two explanations.