Why do the heathen rage, and the people imagine a vain thing?
Heathen — Who did so against David, Acts 4:25, etc.
 The kings of the earth set themselves, and the rulers take counsel together, against the LORD, and against his anointed, saying,
The kings — Herod, and Pilate and others with or after them.
Earth — So called in way of contempt and to shew their madness in opposing the God of heaven.
Set — The word denotes the combination of their counsels and forces.
Anointed — Against the king whom God hath chosen and exalted.
 Let us break their bands asunder, and cast away their cords from us.
And cast — The same thing expressed with more emphasis. Let us not only break off their yoke and the cords by which it is fastened upon us, but let us cast them far away.
 He that sitteth in the heavens shall laugh: the Lord shall have them in derision.
Sitteth — As the king of the whole world.
Heavens — As an evidence both of God's clear and certain knowledge of all things that are done below, and of his sovereign and irresistible power.
Laugh — Shall despise them and all their crafty devices.
 Yet have I set my king upon my holy hill of Zion.
Yet — Notwithstanding all their artifices and combinations.
My king — Who ruleth in my stead, and according to my will, and for my glory.
Zion — Over my church and people. Zion strictly taken, was an hill on the north part of Jerusalem, where there was a strong fort, called the city of David, but in a more large sense it is put for the city of Jerusalem, for the temple of Jerusalem, built upon the hill of Moriah, which was either a part of mount Sion, or adjoining to it; for the church of the Jews, and for the Christian church.
 I will declare the decree: the LORD hath said unto me, Thou art my Son; this day have I begotten thee.
The decree — The will and appointment of God concerning this.
My sin — Which tho' it may in some sort be said to, or of David, yet much more properly belongs to Christ, who is commonly known by this title both in the Old and New Testament, and to whom this title is expressly appropriated by the holy ghost, who is the best interpreter of his own words, Hebrews 1:5.
This day — This may be understood either, 1. Of his eternal generation. This day, from all eternity, which is well described by this day, because in eternity there is no succession, no [yesterday,] no [tomorrow,] but it is all as one continued day or moment without change or flux; or, 2. Of the manifestation of Christ's eternal son-ship in time; which was done both in his birth and life, when his being the son of God was demonstrated by the testimony of the angel, Romans 1:4.
 Ask of me, and I shall give thee the heathen for thine inheritance, and the uttermost parts of the earth for thy possession.
Earth — Not only the Jewish nation, but the whole world.
 Thou shalt break them with a rod of iron; thou shalt dash them in pieces like a potter's vessel.
Them — Those that will not quietly submit to thee, shall be crushed and destroyed by thee. This was in part fulfilled, when the Jews who persisted in unbelief, were destroyed by the Romans power: And in the destruction of the Pagan power, when the Christian religion came to be established. But it will not be compleatly fulfilled, 'till all opposing power and principality be put down.
 Be wise now therefore, O ye kings: be instructed, ye judges of the earth.
Now — While you have time for repentance and submission.
 Serve the LORD with fear, and rejoice with trembling.
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.
 Kiss the Son, lest he be angry, and ye perish from the way, when his wrath is kindled but a little. Blessed are all they that put their trust in him.
Kiss — In token of your subjection and adoration; whereof this was a sign among the eastern nations.
The son — The son of God.
Ye perish — Be taken out of the way by death or destruction.
Wrath — The least degree of his anger is terrible.