Job 37:18

37:18 will you, with him, spread out ¹  the clouds,

solid as a mirror of molten metal?

[37:18]  ¹ tn The verb means “to beat out; to flatten,” and the analogy in the next line will use molten metal. From this verb is derived the word for the “firmament” in Gen 1:6-8, that canopy-like pressure area separating water above and water below.