Psalms

This Psalm is messianic and millennial.  Jesus and Peter both wrote that David wrote this Psalm.  See Matthew 22:43; Mark 12:36; Luke 20:42; Acts 2:33-35.  It is the most quoted Psalm in the New Testament.  There is no clear indication as to the what was going on in David's life when he wrote this Psalm.  Some suggest 2 Samuel 7:4-17 where God speaks the Davidic covenant to David saying that his throne would be established forever.  Whatever the circumstances, we can look at this and see that it refers to the messiah. 

-A Psalm of David.

¹ The LORD said to my Lord,
"Sit at My right hand,
Till I make Your enemies Your footstool."
This passage speaks of the divine nature of Jesus Christ.  He is Lord, He is God.  As the King there was no one in the land David would call lord (Adonai).  Yahewh said this to David's Lord.  Who is David's Lord?  Only Jesus.  Jesus quotes this passage in Matthew 22:43;44.  He asks the Pharisees who's son the messiah is.  They answered the son of David.  Jesus asks how that can be if David calls him Lord.  The father would never call the son lord.  The father would be called lord over the son.  This stumped the Pharisees.  They couldn't figure this out.  They were only looking at the messiah as the son of David, a man.  They were partially correct.  Jesus is also the Son of God.  They did not recognize his deity.  That is how David can look to Him and call Him Lord, because He is the Lord God even though He is also the son of David.

God the Father invites God the Son to sit at His right hand.  This is the place of honor; an honored place in a high and holy setting.  Jesus is seated at the right hand of God the Father but only for a time.  God will bring all mankind into submission.  He will make the enemies of Jesus his footstool.  This is the picture of total submission; to have all enemies under his foot.

² The LORD shall send the rod of Your strength out of Zion.
Rule in the midst of Your enemies!
Jesus will rule on the earthly throne of David in the millennia.  This throne will be in Zion and from that throne He will rule the world.  This is the King of all Kings ruling in the midst of His enemies.  See Isaiah 9:6 and Zech 14:9. 

Psalm 2 says this,

⁷ "I will declare the decree:
The LORD has said to Me,
'You are My Son,
Today I have begotten You.
⁸ Ask of Me, and I will give You
The nations for Your inheritance,
And the ends of the earth for Your possession.
⁹ You shall break them with a rod of iron;
You shall dash them to pieces like a potter's vessel.'"

Even though Jesus will rule in perfect righteousness in this millennial kingdom, there will be a rebellion. 

³ Your people shall be volunteers
In the day of Your power;
In the beauties of holiness, from the womb of the morning,
You have the dew of Your youth.
God's people will be volunteers in the sense that they serve Him willingly.  They won't just submit from fear, but will submit in love.  We will love the Lord 'in the day of Your power'.  This will be a time like no other.  God's people will also be volunteers 'in the beauty of holiness'.  They will be set apart for service to Him.  They will be 'from the womb of the morning'.  This is likely a reference to new volunteers, new believers following their Lord.  They will be common, rising up every day as the dew shows up, seemingly out of nowhere, in great abundance. 

This last passages is rendered ' Your youth are to you as the dew' in the NASB.  The HCSB says, 'the dew of Your youth belongs to you.   And the ESV says, 'and the dew of Your youth will be yours.  I'm not sure anyone really fully understands these passages.   That shouldn't stop us from seeking an answer.  See the treasury of knowledge for Spurgeon's explanation, it is worth the read.

Thy people shall be willing in the day of thy power, in the beauties of holiness from the womb of the morning: thou hast the dew of thy youth. In consequence of the sending forth of the rod of strength, namely, the power of the gospel, out of Zion, converts will come forward in great numbers to enlist under the banner of the Priest King. Given to him of old, they are his people, and when his power is revealed, these hasten with cheerfulness to own his sway, appearing at the gospel call as it were spontaneously, even as the dew comes forth in the morning. This metaphor is further enlarged upon, for as the dew has a sparkling beauty, so these willing armies of converts have a holy excellence and charm about them; and as the dew is the lively emblem of freshness, so are these converts full of vivacity and youthful vigour, and the church is refreshed by them and made to flourish exceedingly. Let but the gospel be preached with divine unction, and the chosen of the Lord respond to it like troops in the day of the mustering of armies; they come arrayed by grace in shining uniforms of holiness, and for number, freshness, beauty, and purity, they are as the dewdrops which come mysteriously from the morning's womb. Some refer this passage to the resurrection, but even if it be so, the work of grace in regeneration is equally well described by it, for it is a spiritual resurrection. Even as the holy dead rise gladly into the lovely image of their Lord, so do quickened souls put on the glorious righteousness of Christ, and stand forth to behold their Lord and serve him. How truly beautiful is holiness! God himself admires it. How wonderful also is the eternal youth of the mystical body of Christ! As the dew is new every morning, so is there a constant succession of converts to give to the church perpetual juvenility. Her young men have a dew from the Lord upon them, and arouse in her armies an undying enthusiasm for him whose "locks are bushy and black as a raven" with unfailing youth. Since Jesus ever lives, so shall his church ever flourish. As his strength never faileth, so shall the vigour of his true people be renewed day by day. As he is a Priest King, so are his people all priests and kings, and the beauties of holiness are their priestly dress, their garments for glory and for beauty; of these priests unto God there shall be an unbroken succession. The realization of this day of power during the time of the Lord's tarrying is that which we should constantly pray for; and we may legitimately expect it since he ever sits in the seat of honour and power, and puts forth his strength, according to his own word, "My Father worketh hitherto, and I work."

-Treasury of David, The

⁴ The LORD has sworn
And will not relent,
"You are a priest forever
According to the order of Melchizedek."
The Lord declared it and it will be done.  Jesus is a priest, but not just another priest.  He is a priest of a different order.  In this order He is both Priest and King.  Unlike the priests of old, who lived, served and died, never resolving anything, Jesus is eternal.  He is a priest forever having offered the perfect sacrifice once for all men.  His work is done.  And for the first time in the history of mankind a priest can sit down with the work complete.  Now He intercedes for us.

Melchizedek is a mystery.  He appears before Abraham as he returns from rescuing Lot.  This story can be read in Genesis 14.  Then the writer of Hebrews uses both Genesis 14 and this Psalm to make the case for Jesus being a pries and king of another order.  Jesus was of the order of Melchizedek.

⁵ The Lord is at Your right hand;
He shall execute kings in the day of His wrath.

⁶ He shall judge among the nations,
He shall fill the places with dead bodies,
He shall execute the heads of many countries.
Now God the Father is at God the Son's right hand.   The Father provides the needs of the Son and He brings the world into submission.  This day of wrath is the Day of the Lord.  It is God pouring out His judgment on the rebellious world.  Nations and kings will be in power, they will believe they have the answers.  God will judge them and His judgments will be righteous.   The unbelieving world will rage against God.

Revelation 19:11; Jeremiah 23:5; Micah 5:2. 

⁷ He shall drink of the brook by the wayside;
Therefore He shall lift up the head.

In the end, this is the picture of the King that now rules the land.  Nothing will distract Him from his task.  With evil defeated He can now pause to drink from the brook.  This may be the waters flowing from Jerusalem (see Zechariah 14:8).  The Lord will lift up the head.  This is God being exalted above all.