He ruleth by his power for ever - literally, “Ruling by his power forever.” The idea is, that he does this constantly; in each age and generation. He never has ceased to rule; he never will. His dominion extends from age to age, and will stretch forward forever. The power which he evinced in delivering his people he retains now, and will retain forever. In that unchanging power, his people may confide; that unchanging power, the wicked should fear.
His eyes behold the nations - All nations; all people. He sees all their conduct. They can conceal nothing from him. They should, therefore, stand in awe. The wicked have much to fear from One who sees all that they do, and who has power to crush and destroy them. Compare the notes at Psalms 11:4.
Let not the rebellious exalt themselves - Be lifted up with pride, or feel secure. They cannot overcome an Almighty God; they cannot escape from his power. The word rebellious here has reference to those who are impatient under the restraints of the law of God, and who are disposed to east off his authority. The admonition is one that may be addressed to all who thus rebel against God, whether they are nations or individuals. Alike they must feel the vengeance of his arm, and fall beneath his power.