The significance of Leviticus 26:19 must be understood in light of the creation account of Genesis 1:1–31. The Hebrew word for firmament
(rāqî‛ǎ) is derived from a root that means, to beat out, to stamp, or to spread out by hammer.
This root word is often used in the context of metalworking. In Leviticus 26:19, the author is using the imagery of metalworking to represent God. He is the divine metalworker who will shut up the heavens.
19 Je briserai l'orgueil de votre force, je rendrai votre ciel comme du fer, et votre terre comme de l'airain.