Kommentar zu Bereschit 1:18

ולהבדיל בין האור ובין החושך, between the period when light begins and the period when darkness begins. Sunrise is the period when light begins, whereas the clear visibility of the stars in the evening is the period when the darkness begins.

ולמשול ביום ובלילה, in order to bring new creatures into life in the “lower” regions of the universe, i.e. these living creatures, as opposed to the plants, required more than the light G’d had created on the first day. Seeing they are more important and more sophisticated beings they require exposure to better light in order to flourish.

And to rule over the day and the night (velimshol bayom ouvalila): The root, mem-shin-lamed (to rule) is connected to the [letter,] bet [after it], as [is the case with] (Genesis 37:8), "will you surely rule over us (timshol banu)." And the intention is that the night and the day be under the rulership of the luminaries as I have explained; and not that they will rule over the lower beings, this one by day and this one by night as is the opinion of Ramban. And this matter still requires much study, and maybe [Ramban] is right; and so did the Psalmist say (Psalms 136:8-9), "for the government of the day... for the government of the night." And it appears that this is what the author of the cantillation marks intended in verse 16, as he wanted to attach "and the small luminary to rule the night" with "and the stars;" as the psalmist [there] said, "and the moon and the stars for the government of the night."