RaMBaN on Bereishit
Bereishit 1:4 And G-d saw the light, that it was good.
Rabbi Shlomo [ Rashi] wrote: "Here too we must depend on the words of the homiletic Agadah. G-d saw that the wicked were unworthy of using the light, and so He set it aside for the righteous in the World to Come. But according to the plain meaning of the verse, explain it thus: He saw that the light was good, and that it was not seemly for it and the darkness to function in a confused manner. He therefore assigned the one's sphere of activity to the daytime and the one's sphere of activity to the nighttime."
But the words of both Rashi and Ibn Ezra are incorrect for if they were, it would appear that there was on the part of G-d a change of mind and new counsel, as if to say that after G-d said, 'Let there be light' and there was light, He saw that it was good, and therefore He divided between it and darkness just as a human being who does not know the nature of something until it comes into existence! Rather, the order followed in the process of creation is that the bringing forth of things into actual existence is called amirah (saying)...
So does it say on the first day when light came into existence, "And G-d saw ... that it was good," meaning He desired its existence forever.
The verse adds "the light" [And G-d saw 'the light' that it was good], because had it just said, "And G-d saw that it was good," it would have referred to the creation of the heaven and the earth, and at that time He had not yet decreed for them permanence, as they did not remain as they were. Instead, from the substance created on the first day, the firmament was made on the second day, and on the third the waters and the dust were separated and the dry land - which He called "earth" - was formed. He then decreed for them permanence, and said concerning them, And God saw that it was good.
Now some commentators have said that this light was created in front of the Holy One, blessed be He, that is to say, in the west, and He immediately caused it to disappear for the period of the night, and afterwards it gave light for the period of the day. This is the reason for the verse, "And there was evening and there was morning," since the night came first and afterwards the day, and both of them came after the existence of the light.
It is further possible that we should say that when the heavens and the earth came forth from naught into existence, as mentioned in the first verse, time came into being, for although our time consisting of minutes and hours is measured in light and darkness, yet from the moment some substance came into existence time was already part of it. If so, after the heavens and the earth were created they so remained for the length of a night without light. Then He said, 'Let there be light,' and there was light, and He decreed that it remain the same period as the first, and that after that it be absent from the elements. Thus, there was evening, and there was morning.
AND GOD CALLED THE LIGHT DAY. The verse states that time was created, and G-d made the length of the day and the length of the night.
The purport of the word vayikra (And He called) is [to indicate that] since Adam later gave names [to all the beasts, the fowl, etc.] it states that those things which were made before his existence were given names by G-d. This is the opinion of Rabbi Abraham ibn Ezra.
The correct interpretation is that the matter of calling a name here indicates the division which bounded them when they assumed their form. Thus did the Rabbis say: " G-d said to the light 'The day shall be your boundary,' [and to darkness He said 'The night shall be your boundary.'"
And Rabbi Abraham ibn Ezra said: "The word vayar (and He saw) has the same meaning here as in Vera'iti ani (And I saw), which refers to the thought in the heart. "And He divided" refers to His giving them different names.
AND G-D DIVIDED THE LIGHT FROM THE DARKNESS. This is not "the darkness" mentioned in the first verse which, as explained above, refers to the element of fire; rather, the "darkness" mentioned here means the absence of light, since God gave a length of time to the light and decreed that it be absent afterwards until it returns.
But this is not correct at all, for in this way they might add a short day to the six days of creation. It is possible, however, to say that the light was created in front of Him, blessed be He, but did not extend over the four elements mentioned [in the second verse, as explained above] and then He divided between it and the darkness by assigning to each a certain period. Light now remained before Him for the length of night, and then in the morning, He caused the light to shine upon the elements. In this way night preceded day.