Put them in fear, O Jehovah. The Septuagint translates mvrh, morah, [nomothetes,] a lawgiver, deriving it from yrh, yarah, which sometimes signifies to teach. [1] But the scope of the passage requires that we should understand it of fear or dread; and this is the opinion of all sound expositors. Now, it is to be considered of what kind of fear David speaks. God commonly subdues even his chosen ones to obedience by means of fear. But as he moderates his rigour towards them, and, at the same time, softens their stony hearts, so that they willingly and quietly submit themselves to him, he cannot be properly said to compel them by fear. With respect to the reprobate, he takes a different way of dealing. As their obduracy is inflexible, so that it is easier to break than to bend them, he subdues their desperate obstinacy by force; not, indeed, that they are reformed, but, whether they will or no, an acknowledgement of their own weakness is extorted from them. They may gnash their teeth and boil with rage, and even exceed in cruelty wild beasts, but when the dread of God seizes upon them, they are thrown down with their own violence, and fall with their own weight. Some explain these words as a prayer that God would bring the nations under the yoke of David, and make them tributaries to his government; but this is a cold and forced explanation. The word fear comprehends in general all the plagues of God, by which is repulsed, as by the heavy blows of a hammer, the rebellion of those who would never obey him except by compulsion. There follows next the point to which the nations must be brought, namely, to acknowledge themselves to be mortal men. This, at first sight, seems to be a matter of small importance; but the doctrine which it contains is far from being trifling. What is man, that he dares of himself to move a finger? And yet all the ungodly run to excess as boldly and presumptuously as if there were nothing to hinder them from doing whatever they please. It is certainly through a distempered imagination that they claim to themselves what is peculiar to God; and, in short, they would never run to so great excess if they were not ignorant of their own condition. David, when he beseeches God to strike the nations with terror, that they may know that they are men, [2] does not mean that the ungodly will profit so much under the rods and chastisements of God as to humble themselves truly and from the heart; but the knowledge of which he speaks just means an experience of their own weakness. His language is as if he had said, Lord, since it is their ignorance of themselves which hurries them into their rage against me, make them actually to experience that their strength is not equal to their infatuated presumption, and after they are disappointed of their vain hopes, let them lie confounded and abased with shame. It may often happen that those who are convinced of their own weakness do not yet reform; but much is gained when their ungodly presumption is exposed to mockery and scorn before the world, that it may appear how ridiculous was the confidence which they presumed to place in their own strength. With respect to the chosen of God, they ought to profit under his chastisements after another manner. It becomes them to be humbled under a sense of their own weakness, and willingly to divest themselves of all vain confidence and presumption. And this will be the case if they remember that they are but men. Augustine has well and wisely said, that the whole humility of man consists in the knowledge of himself. Moreover, since pride is natural to all, God requires to strike terror into all men indiscriminately, that, on the one hand, his own people may learn to be humble, and that, on the other hand, the wicked, although they cease not to elevate themselves above the condition of man, may be put back with shame and confusion.

Footnotes

1 - The Chaldee version reads fear, but the Syriac, Ethiopic, and Vulgate versions follow the Septuagint. The Arabic employs a word of nearly the same import, signifying a doctor or teacher of the law. In it is, "O Lord set a schoolmaster over them." Augustine and Jerome, who adopted the reading of the Septuagint, render the words, "Set, O Lord, a lawgiver over them;" and it was their opinion that lawgiver means antichrist, to whom God in his wrath gave dominion over the nations. According to others, lawgiver means Christ. Dr Horsley reads, "O Jehovah, appoint thou a teacher over them." Ainsworth and Dr Adam Clarke adopt the same rendering, and view the words as a prayer that the nations may learn humility and piety, that they may know their accountability to God, and become wise unto salvation.

2 - The original word is 'nvs, enosh; and therefore it is a prayer that they may know themselves to be but miserable, frail, and dying men. The word is in the singular number, but it is used collectively.

Put them in fear, O Lord - From this it is evident that the enemies of the psalmist were bold, daring, confident in their own strength, and in the belief that they would succeed. He prays, therefore, that these bold and daring invaders of the rights of others might be made to stand in awe, and to tremble before the great and terrible majesty of God; that they might thus have just views of themselves, and see how weak and feeble they were as compared with Him.
That the nations may know - The nations particularly referred to in this psalm as arrayed against the writer.
Themselves to be but men - That they may see themselves as they are - poor, feeble creatures; as nothing when compared with God; that instead of their pride and self-confidence, their belief that they can accomplish any purpose that they choose, they may see that they are not like God, but that they are frail and feeble mortals. The psalmist seems to have supposed that if they understood this, they would be humbled and would desist from their purposes; and he therefore prays that God would interpose and show them precisely what they were. If men understood this, they would not dare to arrayy themselves against their Maker.

Put them in fear - שיתה יהוה מורה להם shithah Yehovah morah lahem, "O Lord, place a teacher among them," that they may know they also are accountable creatures, grow wise unto salvation, and be prepared for a state of blessedness. Several MSS. read מורא morre, fear; but teacher or legislator is the reading of all the versions except the Chaldee. Coverdale has hit the sense, translating thus: O Lorde, set a Scholemaster over them; and the old Psalter, Sett Lorb a brynger of Law abouen tham.
That the nations may know themselves to be but men - אנוש enosh; Let the Gentiles be taught by the preaching of thy Gospel that they are weak and helpless, and stand in need of the salvation which Christ has provided for them. This may be the spirit of the petition. And this is marked by the extraordinary note Selah; Mark well, take notice. So the term may be understood.
"This whole Psalm," says Dr. Horsley, "seems naturally to divide into three parts. The first ten verses make the First part; the six following, the Second; and the remaining four the Third.
"The First part is prophetic of the utter extermination of the irreligious persecuting faction. The prophecy is delivered in the form of an Επινικιον, or song of victory, occasioned by the promise given in the fifteenth verse of the tenth Psalm; and through the whole of this song the psalmist, in the height of a prophetic enthusiasm, speaks of the threatened vengeance as accomplished.
"The Second part opens with an exhortation to the people of God to praise him as the Avenger of their wrongs, and the watchful Guardian of the helpless, and, as if the flame of the prophetic joy which the oracular voice had lighted in the psalmist's mind was beginning to die away, the strain is gradually lowered, and the notes of triumph are mixed with supplication and complaint, as if the mind of the psalmist were fluttering between things present and to come, and made itself alternately present to his actual condition and his future hope.
"In the Third part the psalmist seems quite returned from the prophetic enthusiasm to his natural state, and closes the whole song with explicit but cool assertions of the future destruction of the wicked, and the deliverance of the persecuted saints, praying for the event."

Put them in fear, O LORD: [that] the nations may know themselves [to be but] (k) men. Selah.
(k) Which they cannot learn without the fear of your judgment.

Put them in fear, O Lord,.... Who are, a bold, impudent, fearless generation of men; who, like the unjust judge, neither fear God nor regard men, therefore the psalmist prays that God would inject fear into them, who only can do it; and this will be done at Babylon's destruction, when the antichristian kings, merchants, and seafaring men, will stand afar off for fear of her torment, Revelation 18:10;
that the nations may know themselves to be but men; and not God, and have no power against him; see Isaiah 31:3; the sense is, that the antichristian nations, who oppose themselves to Christ and his people, may know that they are but frail, mortal, miserable men, as the word (q) signifies; and that he who is at the head of them, the man of sin, is no other, though he exalts himself above all that is called God, 2-Thessalonians 2:4; or these words are a prayer for the conversion of many among the nations, and may be rendered, "put, O Lord, fear in them" (r); that is, the true grace of fear, "that the nations may know" themselves, their sin and guilt and danger, and know God in Christ, and Christ, and the way of salvation by him; for at the word "know" should be a stop, concluding a proposition, since the accent "athnach" is there; and then follows another, "they are men. Selah": destitute of the fear and grace of God, are capable of it, but cannot give it to themselves.
Selah; on this word; see Gill on Psalm 3:2.
(q) "mortales esse", Junius & Tremellius, Piscator, Gejerus; "homines miseri", Cocceius, Michaelis; "sorry men", Ainsworth. (r) "pone timorem eis", so Junius and Tremellius, Piscator, Pagninus, Montanus, Cocceius, Ainsworth.

By their effectual subjection, make them to realize their frail nature (Psalm 8:4), and deter them from all conceit and future rebellion.