Sforno on Genesis 1:16/ספורנו על בראשית א׳:ט״ז

1ויעש...ויתן...להאיר...ולמשול..ולהבדיל..כי טוב, all of these expressions refer to the luminaries and the other stars. The Torah first writes: ויעש, seeing that up until that point sun and moon had simply been part of all the other celestial bodies which had been created on the second day, or of “heaven,” whose creation had already been reported in verse 1. This is the reason why at this stage the Torah does not call the development of these luminaries an act of creation, ויברא or something similar, but merely writes ויעש, which describes the completion of a process that had already been begun previously. At this stage, G’d singled out these two luminaries from among all the planets and assigned them their function

2The word כי טוב, “that it was good,” describes G’d’s impression after He had removed these luminaries from their original place in the universe, given them spherical shape so that they can orbit, and function as luminaries.