David having, as a preacher of the judgments of God, set forth the vengeance which God would take upon his enemies proceeds now, in the character of a prophet and teacher, to exhort the unbelieving to repentance, that they may not, when it is too late, be compelled to acknowledge, from dire experience, that the divine threatenings are neither idle nor ineffectual. And he addresses by name kings and rulers, who are not very easily brought to a submissive state of mind, and who are, besides, prevented from learning what is right by the foolish conceit of their own wisdom with which they are puffed up. And if David spare not even kings themselves, who seem unrestrained by laws, and exempted from ordinary rules, much more does his exhortation apply to the common class of men, in order that all, from the highest to the lowest, may humble themselves before God. By the adverb now, he signifies the necessity of their speedy repentance, since they will not always be favored with the like opportunity. Meanwhile, he tacitly gives them to understand, that it was for their advantage that he warned them, as there was yet room for repentance provided they made haste. When he enjoins them to be wise, he indirectly condemns their false confidence in their own wisdom as if he had said, The beginning of true wisdom is when a man lays aside his pride, and submits himself to the authority of Christ. Accordingly, however good an opinion the princes of the world may have of their own shrewdness, we may be sure they are arrant fools till they become humble scholars at the feet of Christ. Moreover, he declares the manner in which they were to be wise, by commanding them to serve the Lord with fear. By trusting to their elevated station, they flatter themselves that they are loosed from the laws which bind the rest of mankind; and the pride of this so greatly blinds them as to make them think it beneath them to submit even to God. The Psalmist therefore, tells them, that until they have learned to fear him, they are destitute of all right understanding. And certainly, since they are so much hardened by security as to withdraw their obedience from God, strong measures must at the first be employed to bring them to fear him, and thus to recover them from their rebelliousness. To prevent them from supposing that the service to which he calls them is grievous, he teaches them by the word rejoice how pleasant and desirable it is, since it furnishes matter of true gladness. But lest they should, according to their usual way, wax wanton, and, intoxicated with vain pleasures, imagine themselves happy while they are enemies to God, he exhorts them farther by the words with fear to an humble and dutiful submission. There is a great difference between the pleasant and cheerful state of a peaceful conscience, which the faithful enjoy in having the favor of God, whom they fear, and the unbridled insolence to which the wicked are carried, by contempt and forgetfulness of God. The language of the prophet, therefore, implies, that so long as the proud profligately rejoice in the gratification of the lusts of the flesh, they sport with their own destruction, while, on the contrary, the only true and salutary joy is that which arises from resting in the fear and reverence of God.

Serve the Lord with fear - With reverence, and with deep apprehensions of the consequences of not serving and obeying him. That is, serve him in not opposing, but in promoting his purpose of establishing a kingdom under the Messiah, with the deep apprehension that if you do not do it, he will arise and crush you in his wrath.
And rejoice - Prof. Alexander renders this "shout," and supposes that it refers to the customary recognition of a present sovereign. The word used - גיל gı̂yl - means properly to move in a circle, to revolve; and then to dance in a circle, to exult, to rejoice. Then, according to Gesenius, it means to tremble, to fear, from the leaping or palpitation of the heart Job 37:1; Hosea 10:5; Psalm 29:6. Gesenius renders it here "fear with trembling." The common translation, however, better expresses the sense. It means that they should welcome the purposes of Yahweh, and exult in his reign, but that it should be done with a suitable apprehension of his majesty and power, and with the reverence which becomes the public acknowledgment of God.
With trembling - With reverence and awe, feeling that he has almighty power, and that the consequences of being found opposed to him must be overwhelming and awful. The duty here enjoined on kings and rulers is that of welcoming the purposes of God, and of bringing their influence - derived from the station which they occupy - to bear in promoting the reign of truth upon the earth - a duty binding on kings and princes as well as on other men. The feelings with which this is to be done are those which belong to transactions in which the honor and the reign of God are concerned. They are mingled feelings, derived from the mercy of God on the one hand, and from his wrath on the other; from the hope which his promise and purpose inspires, and from the apprehension derived from his warnings and threatenings.

Serve the Lord with fear - A general direction to all men. Fear God with that reverence which is due to his supreme majesty. Serve him as subjects should their sovereign, and as servants should their master.
Rejoice with trembling - If ye serve God aright, ye cannot but be happy; but let a continual filial fear moderate all your joys. Ye must all stand at last before the judgment-seat of God; watch, pray, believe, work, and keep humble.

Serve the Lord with fear,.... Not the creature, neither more, nor besides, nor with the Creator; God and mammon cannot both be served; nor any fictitious and nominal deities, the idols of the Gentiles, who are not gods by nature; but the true Jehovah, the one and only Lord God, he only is to be worshipped and served, even Father, Son, and Spirit. Here it may be understood either of the Lord Christ, the Son of God, who is to be served by the kings and judges of the earth, he being King of kings, and Lord of lords; or rather of Jehovah the Father, since the Son seems to be distinguished from him in Psalm 2:12, and the service these persons are called unto lies not in the discharge of any office in the church, as in preaching the word, which is serving God in the Gospel of his Son; and hence the ministers of the word are eminently called the servants of the most high God; for kings and judges are not required hereby to lay aside their crowns and sceptres, and leave their seats of justice, and become preachers of the Gospel; but in acting according to the will of God revealed in his word, and in the whole worship of him, both internal and external: and this is to be done "with fear", not with fear of man, nor with servile fear of God, but with a godly and filial fear, with a reverential affection for him, and in a way agreeable to his mind and will; with reverence and awe of him, without levity, carelessness, and negligence;
and rejoice with trembling; some reference may be had to the joy in public worship, as at sacrifices and festivals, and the music in divine service under the law; and the singing of psalms and hymns and spiritual songs under the Gospel; and especially to the Gospel dispensation itself, which is a time of joy and rejoicing; the Gospel is good tidings of great joy; the kingdom of God is not in things external, but in joy in the Holy Ghost; and, above all, respect is had to a rejoicing in Christ Jesus, in his person, righteousness, and salvation: and which is consistent with "trembling"; not with a fearful looking for of judgment, but with modesty and humility; in which sense this word, when joined with "fear" as here, is used Philippians 2:12, and stands opposed to pride, haughtiness, and arrogance; men should so rejoice in Christ as to have no confidence in the flesh, or assume any degree of glory to themselves, or have any rejoicing in themselves, but wholly in Christ, giving all the glory of what they have to him.

Fear - With an awful sense of his great and glorious majesty. Rejoice - Do not esteem his yoke your dishonour and grievance; but rejoice in this inestimable grace and benefit. Trembling - This is added to warn them of taking heed that they do not turn this grace of God into wantonness.