Thou hast set a bound that they may not pass over - See Job 26:10, note; Job 38:10-11, note.

That they turn not again to cover the earth - As it was before the dry land appeared; or as the earth was when "darkness was upon the face of the deep" Genesis 1:2, and when all was mingled earth and water. It is "possible" that in connection with this, the psalmist may also have had his eye on the facts connected with the deluge in the time of Noah, and the promise then made that the world should no more be destroyed by a flood, Genesis 9:11, Genesis 9:15.

Thou hast set a bound that they may not pass - And what is this bound? The flux and reflux of the sea, occasioned by the solar and lunar attraction, the rotation of the earth on its own axis, and the gravitation of the waters to the center of the earth. And what is the cause of all these? The will and energy of God. Thus the sea is prevented from drowning the earth equally where there are flat shores as where the sea seems hemmed in by huge mounds of land and mountains. The above, not these, are the bounds which it cannot pass, so that they cannot turn again to cover the earth.

Thou hast set a bound, that they may not pass over,.... The Targum adds,

"to the rolling waves of the sea.''

Set doors with bolts and bars, cliffs, rocks, and shores: and, what is more surprising, sand, which is penetrable, flexible, and moveable, is set as a perpetual bound to the raging ocean and its waves, which they cannot pass over: see Job 38:8. So the Lord has set a bound to the proud waters of afflictions, and says, Thus far shall ye go, and no farther; and to the life of man, which he cannot exceed, Job 14:5. But he has given man a law, as a rule to walk by, as the boundary of his conversation, and this he transgresses; in which he is less tractable than the raging sea and its waves. That they turn not again to cover the earth; as they did when it was first made, Psalm 104:6 that is, not without the divine leave and power; for they did turn again and cover the earth, at the time of the flood; but never shall more. Some think there is no need to make this exception; since this was written after the flood, and when God had swore that the waters should no more go over the earth, Isaiah 54:9.

Thou hast set a bound that they may not pass over; that they turn not again to cover the earth.

104:9 A bound - Even the sand of the sea - shore.

104:1-9 Every object we behold calls on us to bless and praise the Lord, who is great. His eternal power and Godhead are clearly shown by the things which he hath made. God is light, and in him is no darkness at all. The Lord Jesus, the Son of his love, is the Light of the world.