Once again, a solemn declaration is made by the Lord. It is even emphasized. Yes, truly, a king will come who may fulfill the priestly office also. In David’s time this was simply not done. Priests came from the tribe of Levi, and woe if a non-Levite dared to burn incense in the holiness of the temple. King Uzziah did this, and he ended up with a lifelong affliction of leprosy (see 2 Chronicles 26:16–21).
The king-priest whom the Lord promises here is therefore unique. He is of the level of Melchizedek. We read of him in Genesis 14:1–24, that he was king of Salem and priest of God, the Most High. In that capacity he blessed Abram. And now suddenly someone appears who has the same combination of offices. How surprised David and his contemporaries will have been.
Who is this person and when does he appear on the world stage?
He will come; the Lord swore with an oath, but how and when? We find the answer in the New Testament. Especially in the book of Hebrews we find much information about this. Jesus is central in the book of Hebrews. Not only does he sit at God’s right hand (Hebrews 1:13 which is a quote from Psalm 110:1), but he is also a priest there, after the order of Melchizedek (Hebrews 5:6). In Hebrews 7 we read another quote from Psalm 110 and this conclusion: For it was indeed fitting that we should have such a high priest, holy, innocent, unstained, separated from sinners, and exalted above the heavens
(Hebrews 7:26).
How wonderful it is for us, people, to have Jesus, the king-priest! Whoever entrusts himself to him has the future. Consequently, he is able to save to the uttermost those who draw near to God through him, since he always lives to make intercession for them
(Hebrews 7:25; read Hebrews 4:14–16 also).
4 The LORD has sworn and will not change his mind, “You are a priest forever after the order of Melchizedek.”