You are priest forever, in the order of Melchizedek.

Psalm 110:1-7
Describe the coming Messiah authority and victory over all kings.
Your troops will be willing on your day of battle. Arrayed in holy majesty(神聖威嚴 in holy garments), from the womb of the dawn(as from the womb of the morning) you will receive the dew of your youth( thy youth (vigor) shall be as the dew.).
The Lord has sworn and will not change his mind:"You are priest forever, in the order of Melchizedek."
He will judge the nations , heaping up the dead and crushing the ruler of the whole earth.
He will drink from a brook beside the way; therefore he will lift up his head.
Why?
v7: He shall drink of the brook in the way - The design here seems to be to represent the Messiah as a victorious king and conqueror pursuing his enemies. In the previous verse the psalmist had represented him under the image of one engaged in battle, and slaying his enemies with a great slaughter. He here represents him as pursuing those who should escape from the battle, and as pursuing them without fainting or exhaustion. He is like one who finds abundant springs and streams of water in his journeyings; who refreshes himself at those fountains and streams; who, therefore, is not faint and weary. He pursues his foes vigorously and with success.
It is seen as pointing to God's coming King:the Christ.
How?
Jesus Christ is the victory King and priest forever, his people will array in holy majesty. Praise be to the Lord and Jesus Christ.