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 and I will break the pride of your power, and I will make your heavens like iron and your earth like bronze.