Which alone spreadeth out the heavens - As an expanse, or a curtain; see the notes at Isaiah 40:22.
And treadeth upon the waves of the sea - Margin, “Heights.” So it is in the Hebrew. It means the “high waves;” that is, he walks upon the waves of the ocean when lifted up by a storm. This is spoken of here as a proof of the greatness of God; and the meaning of all is, that he is seen in the storm, in the heaving ocean, when the heavens are black with tempest, and when the earth is convulsed. It may be added here, that the Lord Jesus walked amidst the howling winds on the lake, and thus gave evidence that he was God; Matthew 14:25. “The Egyptian hieroglyphic for what was not possible to be done, was a man walking on the water.” Burder. Dr. Good, and some others, render this, “on the mountains.” But the more correct rendering is given in the common version. The Hebrew word rendered “waves” (במה bâmâh) indeed properly means a height, a lofty place, a mountain; but the comparison of waves with a mountain, is common in all languages. So we speak of waves “mountain-high,” or as high as mountains. So Virgil, Aeneid i. 105,
Insequitur cumulo praeruptus aquae mons.
Similar to this, is the expression occurring in Homer, κύματα ἶσα ὄρεσσιν kumata isa oressin; and so Apollonius, i. 521 - ἅλὸς ἄκρον chalos akron. The Septuagint renders it, “who walketh upon the sea as upon a pavement.”