“For it is witnessed of him, ‘You are a priest forever, after the order of Melchizedek.’”
This quote comes from Psalm 110:4. The entirety of this psalm is related to the aspect of the promised messiah king. It is the psalm where David calls the Messiah, Lord. The one who has witnessed this of Jesus is God Himself. “The Lord has sworn and will not change his mind.” Jesus is a Meldchizedekian priest. That priest (Jesus, in this case) is an eternal priest. He is a priest not because of his lineage but because of an everlasting life.
We have a contrast of priests appointed by the Law or a priest appointed by God. Since there would be a conflict with this arrangement, God solved it by ending the Law and bringing in a better covenant, which does allow a Melchizedekian priest.
Task for Today: Acknowledge that God, as the giver of the Law, could take the Law away. Accept that He did that in order to appoint His Son as the high priest. This allows Jesus to offer the only sacrifice that can eternally forgive sin. Thank you, God, for your unspeakable gift.