Or HaChaim on Genesis 1:7/אור החיים על בראשית א׳:ז׳

1And God made the firmament: This verse should not have been stated; since the verse before this already stated, "And God said, etc." and it should have finished by stating, "and it was so." And I also saw that it was not justified to state "and it was so" after it stated, "And God made." Rather, after stating, "And God said," [such a phrase] would tell us that He said and it was.

2And it appears that three tasks were done with the firmament: The first was the creation of its substance's existence in reality, and this is what was created on the first day in the first proclamation.

3And the second is that that God said to it that it should make a firmament, the explanation [of which] is that it should stretch out and make a partition and God measured the [appropriate] size of its stretching, so that it would suffice to separate between the waters and the waters; and that is what is stated in the verse before this.

4And the third is that, since the heavens are spherical and slanted, we cannot say that the firmament would be different than all [the rest of] the heavens, and in the statement that states, "let there be a firmament," He only said said that it should stretch out, but the order of its setup - whether it be stretched out like a straight partition or one slanted on its ends or whether it inclines to one of the four corners of the world - this is not understood from the statement of God, when He said, Let there be a firmament. For this reason, He went back and stated, "And He made;" the explanation [of which] is that he adjusted the order of its arrangement according to the order of the adjustment of the heavens, which are like an upside down bowl facing down and their back is upwards, for reasons that are known to the Creator of the world. And He went back and stated, "and He separated, etc." since the order of its formation to which the Creator set it up is the opposite of the adjacent statement, that "He separated between, etc," since an [object] arranged like this does not block out between these two waters. For this reason, it states that even if He made it in this arrangement, nonetheless, "and He separated between, etc." And about these two (the second and third) items, the verse stated, "And He made," [meaning] that he fixed it according to the order that was correct in His eyes, and that He created in it an invention that would be able [to accomplish His plan] even with this arrangement.

5And He was precise in stating, "which were above, etc." to say that even though it was made in this arrangement, it separated [also] between the waters above it, a reality that would [normally] not be able to exist in the world. And after all this, He stated, "and it was so," [which] goes back on verse 1 and 2; since when He told it to spread, so was it, and when He told it to be a separation - even if its setup does not allow for it to separate in this manner, according to nature, as mentioned - "and it was so." Or it is possible that the reason it delayed stating, "and it was so" until the [end of the] verse [of] "And He made," was that He did not want to state, "and it was so," until He completed the act in all the details of [its] creation.

6And after I wrote all this, I found that an explicit verse of the Bible testifies to our explanation, since it is written (Isaiah 42:5), "So said etc., Creator of the heavens and who unfolded them;" behold it mentioned two things, the creation by itself and the unfolding by itself. And this is what I explained about the first and second [tasks], since in the first day was the creation and in the second day was the unfolding, and within [that] was the unfolding and its manner, which are the two things that we hinted to.

7And I saw the statement of our Rabbis, of blessed memory, in Bereishit Rabbah 4:6, and this is what they said, "'And God made the firmament;' this is one of the verses [about] which Ben Zoma shook the world, [asking] is it not that the heavens were made in one statement by the word of God?" And [yet] according to our approach, 'and the earth was quieted' from its shaking; and perhaps that which Ben Zoma shook the world was before he resolved the verses, but after the resolution of the verses, 'the earth was quieted' [and] calm.

8Or one could say in the following way, according to what we have explained on the verse, "And God said, 'let the waters gather, etc.," that there are two [types of] water, one male and one female; and according to this, from the perspective that all the waters were mixed in the way that the light and darkness were mixed, 'a bit here and a bit there,' as they, of blessed memory, said (Bereishit Rabbah 3), "'And God separated between the light, etc.,' so too with the higher (elyonim) waters" - the explanation [of which] is the better (meulim) waters, and these are the male - "mixed with the lower waters" - lower in their status; and so God now said that the firmament should make two separations: the first one that it separate one from the other - according to what the Holy One, blessed be He, implanted in it, that it should separate one form the other; and the second one that these [waters] should always be divided by it, [such] that it would split between the two of them; and according to this, its stating, "let there be a firmament within the waters" here refers to the separation that separates between the two waters. And that is why it states "within the waters," since all of the waters were mixed. And afterwards, God arranged the firmament that it should be able to split the two of them perpetually; and that is the second separation, and about both of them the verse stated, "and it was so."