Charles Ellicott Commentary Job 37:18

"Canst thou with him spread out the sky, Which is strong as a molten mirror?" — Job 37:18 (ASV)

( 18 ) Spread out the sky. —Some understand this as the action of the sun in dispersing the clouds, but it seems more probable that it refers to God. “Have you spread out with Him the magnificent dome of heaven?” The words used, however, imply the clouds rather than the cloudless sky which resembles a burnished mirror, so that it is not improbable that the sun may be the subject here and in the following verses.