Lord said unto my Lord. This verse means literally, “Jehovah said unto Adonai.” This is a remarkable conversation between two persons of the Godhead. This psalm is clearly a Messianic psalm, quoted as such at least twelve times in the New Testament. Note especially Matthew 22:43-45, where Christ specifically applies Psalm 110:1 to Himself, claiming that He is not just the son of David, but David's Lord.

right hand. Psalm 110:1 is quoted five times in the New Testament. Note, e.g., Hebrews 1:13: “But to which of the angels said He at any time, Sit on my right hand, until I make thine enemies thy footstool” (also Mark 12:36; Luke 20:42; Acts 2:34). Clearly the psalm prophesies the rejection of Christ by His enemies, then His ascension to the right hand of God, there to wait until time for the subjugation of His enemies. This is the second (Psalm 16:11 is the first) of twenty-one Biblical references to Christ at the right hand of the Father. In addition to the seven already noted, there are seven in the epistles of Paul (Romans 8:34; Ephesians 1:20; Colossians 3:1; Hebrews 1:3; 8:1; 10:12; 12:2), and seven in the other books of the New Testament (Matthew 26:64; Mark 14:62; 16:19; Luke 22:69; Acts 7:55, 56; 1 Peter 3:22).

rod of thy strength. Interestingly, the Hebrew word for “rod” is also frequently translated “tribe,” the connection being that both are branches from a central stock. Thus the “tribe of thy strength” would be the tribe of Judah, which was ordained ultimately as ruler.

people shall be willing. The Hebrew word for “willing” is the same as that for “free-will offerings.” Compare Romans 12:1, 2.

beauties of holiness. The Messiah has donned His eternal “priestly garments” as our eternal High Priest. After “sitting” for two thousand years. He still has “the dew of thy youth,” and will be the same as “yesterday, and to day, and for ever” (Hebrews 13:8). Alternatively, the phrase could refer to the “beautiful sanctuary” (same Hebrew as for “holiness” of the future millennial temple.

order of Melchizedek. This verse is quoted three times in Hebrews (Hebrews 6:20; 7:17, 21), and expounded throughout the seventh chapter of Hebrews, demonstrating thereby the eternal priesthood of Christ. Melchizedek is mentioned elsewhere only in Genesis 14:18-20, identified only as the “priest of the Most High God,” pronouncing God's blessing on Abraham.

The Lord. Jehovah (Psalm 110:4) is again presented here as speaking to Adonai (Psalm 110:5). Thus, “the Lord” (Adonai) is shown as both King (Psalm 110:2) and Priest (Psalm 110:4) eternally, after putting down all enemies.

wound. “Wound” is the same word as “strike through” in Psalm 110:5, in both cases conveying the idea of a complete crushing.

heads. “Heads” should be in the singular. In that day there will be one “head” over “many countries,” the Beast of Revelation 13:4-7, energized and indwelt by Satan. He will finally be crushed to eternal death by Christ, fulfilling the primeval promise of Genesis 3:15.

brook. The “brook” is actually a “river.” Note the contrast: On the cross, Christ thirsted (John 19:28). When He comes with His crown, He shall drink a river!

lift up. Note also: on the cross, He “bowed His head” (John 19:30). On His throne, He will “lift up His head” for evermore in triumph over all His enemies.