Midrash sobre Job 20:27

"And God called the firmament heavens (shamayim)" (Gen. 1:8). Rav says, [shamayim means] fire (aish) and water (mayim) [mixed together]. Rabbi Abba the son of [Rav] Kahanah said in the name of Rav, the Holy One, Blessed be He took fire (aish) and water (mayim), joined them together and made the heavens ((ai)sh+mayim = shamayim). Another version, [although] the word is written "shamayim," [it can be read as shamim ("evaluate")], for they (i.e., the heavens) shamim (evaluate) the actions of the creations. If they merit it then "the heavens will tell his righteousness" (Ps. 97:6), and if not, "the heavens will reveal his sin" (Job 20:27). Another version, [the heavens are called] shamayim because the creations mishtom'mim ("wonder") about them, saying, "What are they made of, are they made of fire, [or] are they made of water? Water or fire?!!!" Rabbi Pinchas in the name of Rabbi Levi said, he came and revealed it, [as it is said], "He lays the beams of his upper chambers in the waters" (Ps. 104.3), thus you must say, they are made of water. "Spices" (samim (סַּמִּֽים), as referenced in Ex. 25:6, connected to the word "בְּשָׂמִים֙", which can be read "spices" or "in heaven") what are these "spices" [that are referenced]? From them [the heavens] turn green and from them they redden, from them they blacken and from them they whiten, and thus the heavens sometimes are green, and sometimes are red, sometimes are black, and sometimes are white. Rabbi Yitzchak said, "shamayim" means "water travels" (sah mayim), a shipment (טְעוֹן) of water. For example, [this is similar] to milk that was placed in a bowl, before a single drop of m'so (a liquid agent used for curdling milk) drips into it, [the milk] moves back and forth, but as soon as a drop of m'so drips into it, it coagulates and stands still, thus [it says], "The pillars of the heavens tremble" (Job 26:11). The heavens stood still [because God] placed m'so inside them, and so "it was evening and it was morning the second day" (Gen. 1:8). Thus Rav said, "[the waters] were wet on the first day, and on the second day they congealed."