And said, Hitherto shalt thou come - This is a most sublime expression, and its full force can be felt only by one who has stood on the shores of the ocean, and seen its mighty waves roll toward the beach as if in their pride they would sweep everything away, and how they are checked by the barrier which God has made. A voice seems to say to them that they may roll in their pride and grandeur so far, but no further. No increase of their force or numbers can sweep the barrier away, or make any impression on the limits which God has fixed.
And here shall they proud waves be stayed - Margin, as in Hebrew, "the pride of thy waves." A beautiful image. The waves seem to advance in pride and self-confidence, as if nothing could stay them. They come as if exulting in the assurance that they will sweep everything away. In a moment they are arrested and broken, and they spread out humbly and harmlessly on the beach. God fixes the limit or boundary which they are not to pass, and they lie prostrate at his feet.

Hitherto shalt thou come - Thus far shall thy flux and reflux extend. The tides are marvellously limited and regulated, not only by the lunar and solar attractions, but by the quantum of time also which is required to remove any part of the earth's surface from under the immediate attractive influence of the sun and moon. And this regulation takes place by means of the rotation of the earth round its own axis, which causes one thousand and forty-two miles of its equator to pass from under any given point in the heavens in one hour; and about five hundred and eighty miles in the latitude of London: so that the attracted fluid parts are every moment passing from under the direct attractive influence, and thus the tides cannot generally be raised to any extraordinary height. The attraction of the sun and moon, and the gravitation of its own parts to its own center, which prevent too great a flux on the one hand, and too great a reflux on the other; or, in other words, too high a tide, and too deep an ebb, are also some of those bars and doors by which its proud waves are stayed, and prevented from coming farther; all being regulated by these laws of attraction by the sun and moon, the gravitation of its own parts from the sun and moon, and the diurnal motion round its own axis, by which the fluid parts, easily yielding to the above attraction, are continually moving from under the direct attractive influence. Here a world of wisdom and management was necessary, in order to proportion all these things to each other, so as to procure the great benefits which result from the flux and reflux of the sea, and prevent the evils that must take place, at least occasionally, were not those bars and doors provided. It is well known that the spring-tides happen at the change and full of the moon, at which time she is in conjunction with and opposition to the sun. As these retire from their conjunction, the tides neap till about three days after the first quadrature, when the tides begin again to be more and more elevated, and arrive at their maximum about the third day after the opposition. From this time the tides neap as before till the third day after the last quadrature; and afterwards their daily elevations are continually increased till about the third day after the conjunction, when they recommence their neaping; the principal phenomena of the tides always taking place at or near the some points of every lunar synodic revolution.

And said, Hitherto shalt thou come, but no further: and here shall thy proud waves be (h) stayed?
(h) That is, God's decree and commandment as in (Job 38:10).

And said, hitherto shalt thou come, but no further,.... The waters of the sea shall spread themselves to such and such shores, and wash them, but go no further; its rolling tides shall go up so far in rivers that go out of it, and then return, keeping exactly to time and place; this is said by Jehovah, the Word of God, and through his almighty power is tended to;
and here shall thy proud waves be stayed; so high and no higher shall they lift up themselves; so far and no farther shall they roll on, than to the boundaries fixed for them; and though they may toss up themselves as proud men toss up their heads, for which, reason pride is ascribed to them, yet they shall not prevail, Jeremiah 5:22; all this may be accommodated to the afflictions of God's people, which are sometimes compared to the waves and billows of the sea, Psalm 42:7; and these issue out of the womb of God's purposes and decrees, and are not the effects of chance; they are many, and threaten to overwhelm, but God is with his people in them, and preserves them from being overflowed by them; he has set the bounds and measures of them, beyond which they cannot go; see Isaiah 27:8; and also to the world, and to the men of it, who are like a troubled sea, Daniel 7:2; and who rise, and swell, and dash against the people of God, being separated from them who were originally mixed with them; but the Lord restrains their wrath and fury, and suffers them not to do his people any harm; whom he has placed in the munition of rocks out of their reach, that those proud waters cannot go over them as they threaten to do; see Psalm 76:10.

stayed--Hebrew, "a limit shall be set to."