Psalm 110


4 The Lord has sworn
and will not change his mind:
“You are a priest forever,
in the order of Melchizedek.”

This verse is soothing because it talks about the eternity of Jesus being our high priest forever, in the order of Melchizedek. Who is Melchizedek? He is mentioned at least twice in the bible.

In Genesis 15, Abram had just defeated an army and was about to face the King of Sodom in war when:

18 Then Melchizedek king of Salem brought out bread and wine. He was priest of God Most High,19 and he blessed Abram, saying,
“Blessed be Abram by God Most High,
Creator of heaven and earth.

20 And praise be to God Most High,
who delivered your enemies into your hand.”
Then Abram gave him a tenth of everything.

Also in Hebrew 7,

1 This Melchizedek was king of Salem and priest of God Most High. He met Abraham returning from the defeat of the kings and blessed him, 2 and Abraham gave him a tenth of everything. First, the name Melchizedek means “king of righteousness”; then also, “king of Salem” means “king of peace.” 3 Without father or mother, without genealogy, without beginning of days or end of life, resembling the Son of God, he remains a priest forever.

4 Just think how great he was: Even the patriarch Abraham gave him a tenth of the plunder!

Such was the repute of Melchizedek, that his name meant king of righteousness and king of peace, that Abram would tithe to him.

Jesus is in the order of Melchizedek, but even better since it is for eternity.