when the waters become hard as stone and the surface of the deep is frozen?
Hitherto God had put such questions to Job as were proper to convince him of his ignorance and short-sightedness. Now he comes, in the same manner, to show his impotency and weakness. As it is but little that he knows, and therefore he ought not to arraign the divine counsels, so it is but little that he can do, and therefore he ought not to oppose the proceedings of Providence.
Commenting on Job 38:25-41
Canst thou bring forth Mazzaroth in his season?.... Which are thought to be the same with "the chambers of the south", Job 9:9; the southern pole (m) with its stars, signified by chambers, because hidden from our sight in this part of the globe; and here by Mazzaroth, from, "nazar", to separate, because separated and at a distance from us; some think (n) the twelve...
The unfrozen waters are hid under the frozen, as with a covering of stone. frozen--literally, "is taken"; the particles take hold of one another so as to cohere.