PSALM 110 Our TRIUNE GOD

Psalm 110   (Vulgate 109)
The Lord (The Father)  said to my Lord (Christ),
"Sit at My right hand"

Jesus is begotten from the Father before all time
( before the morning star ) 
and is the "ETERNAL SON " of the "FATHER"

In this Psalm of David
David calls the future king "my Lord".
Since the future king is the Messiah,
David is calling the Messiah "my Lord" !

Psalm 110:3 NCV
Yours is royal dignity in the day of your birth;
in holy splendor, before the day star
like the dew, I have begotten you.

Psalm 110 (Septuagint 109) is a Royal Psalm and
contains prophecy concerning the Melchizedek
 priesthood of our Lord Jesus  Christ .

In Genesis 14:18 Melchizedek is king of Salem
                            and priest of God Most High
bringing out bread and wine he blesses Abram.
See Hebrews 7 regarding the permanence of the
Royal Priesthood of the Lord Jesus.

Hebrews 1:8 begins "But of the Son he says;---"
and quotes Ps110:1  and Psalm 45:6-7 precisely.

Psalm 110:1 ESV    The LORD says to my Lord;
"Sit at my right hand until I make your enemies your footstool"

Psalm 45:6-7 ESV Your throne, O God, is for ever and ever.
The sceptre of your kingdom is a sceptre of uprightness;
you have loved righteousness and hated wickedness.
Therefore God, your God, has anointed you
with oil and gladness beyond your companions.

Since we know from Isaiah 63;10 that God's people
"rebelled and grieved his Holy Spirit"
we can distinguish God the Father, God the Son,
and God the Holy Spirit, while understanding that
God-With-Us comprises all three.

David, the divinely inspired writer of Psalm 110
predicted that the future seed of David was to be our Messiah.
Our Lord Jesus is,in the flesh, descended from David,
and is David's Lord and our Lord. 

Psalm 2:7  ESV and SAAS
The LORD said to me
"You are my son; today I have begotten you.

St Matthew 3:17 KJV
And lo a voice from heaven, saying, 
This is my beloved Son, in whom I am well pleased.