“God said: Let there be a firmament in the midst of the water” – the Rabbis say it in the name of Rabbi Ḥanina, Rabbi Pinḥas, and Rabbi Yaakov bar Avin in the name of Rabbi Shmuel bar Naḥman: When the Holy One blessed be He said: “Let there be a firmament in the midst of the water,” the middle drop [of water] congealed and thereby the lower heavens and the upper highest heavens came about. Rav said: Their substance on the first day1When God “created the heavens” (Genesis 1:1). was damp, and on the second day they congealed.
“Let there be a firmament” – let the firmament harden. Rabbi Yehuda bar Rabbi Simon said: Let there be a lining for the firmament [rakia], as it says: “They flattened [vayraku] the sheets of gold” (Exodus 39:3). Rabbi Ḥanina said: Fire emerged from on High and passed over the surface of the firmament.2Drying it, in accordance with the opinion of Rav. When Rabbi Yoḥanan would reach this verse: “With His wind, the heavens are enhanced” (Job 26:13), he would say: Rabbi Ḥanina taught me well.
Rabbi Yudan ben Rabbi Shimon said: The fire emerged from on High and burnished the surface of the firmament. Rabbi Berekhya said in the name of Rabbi Abba bar Kahana: The act of Creation came to teach something about the giving of the Torah, but ultimately learned something from it. “Like [the day of] a splitting fire” (Isaiah 64:1)3The verse is speaking of the giving of the Torah, and describes that day as being like another day, one of fire splitting something in two. – when did fire split between what was above and what was below, was it not at the giving of the Torah?4And the verse compares that day to another day, one of a splitting fire – namely, the day of the creation of the heavens. That is a rhetorical question. So it was at the creation of the world.