Psalms 110:4

The Lord hath sworn - Has most firmly purposed, and will most certainly perform it, feeling himself bound by his purpose, as an honest man would by his oath.

And will not repent - Will never change this purpose; it is perfectly without condition, and without contingency. Nothing is left here to the will of man or angel. Christ shall be incarnated, and the Gospel of his salvation shall be preached over the whole earth. This is an irresistible decree of that God who loves mankind.

Thou art a priest for ever - The word כהן cohen signifies, not only a priest, but also a prince; as, in the patriarchal times, most heads of families had and exercised both political and sacerdotal authority over all their descendants. Every priest had a threefold office:

1. He was an instructor of the family or tribe over which he presided.

2. He offered sacrifices for the sins of the people, to reconcile them to God, and give them access to his presence.

3. He was their mediator, and interceded for them. So is Christ, the grand, the universal Instructor, by his word and Spirit; the Lamb of God, who, by his sacrificial offering of himself, takes away the sin of the world, and still continues to exhibit himself before the throne in his sacrificial character; and also the great Mediator between God and man: and in these characters he is a Priest for ever. He will instruct, apply the sacrificial offering, and intercede for man, till time shall be no more.

After the order of Melchizedek - For the elucidation of this point, the reader is requested to refer to the notes on Genesis 14:18, Genesis 14:19, and to the observations at the end of that chapter, where the subject, relative to the person, name, and office of this ancient king, is fully discussed; and it will be necessary to read that note, etc., as if appended to this place.

Melchizedek was king of Salem, that is, king of Jerusalem; for Salem was its ancient name: but שלם salem signifies peace, and צדק tsedek, righteousness. Christ is styled the Prince of peace; and he is the king that rules in the empire of righteousness; and all peace and righteousness proceed from him, Hebrews 7:2.

He is priest after the order of Melchizedek - after his pattern; in the same kind or manner of way in which this ancient king was priest.

Calmet properly observes that there were three orders of priesthood.

1. That of royalty. All ancient kings being, in virture of their office, priests also. This seems to have been considered as the natural right of royalty, as it obtained in almost every nation of the earth, from the beginning of the world down to the end of the Roman empire.

2. That of the first-born. This right appertained naturally to Reuben, as the first-born in the family of Jacob.

3. That of the Levites, instituted by God himself, and taken from Reuben, because of his transgression. The Levitical priesthood ended with the Jewish polity; and that also of the first-born, which had been absorbed in it.

This order, therefore, was not perpetual; it was intended to last only for a time. But that of royalty is perpetual, though not now in general use, because founded in what is called natural right. It is, therefore, according to this most ancient order, that Christ is a Priest for ever. The kings of England as heads of the Church appointing all bishops, continue to assume, in a certain way, this original right.

continued...

The Lord hath sworn - He has confirmed the appointment of the Messiah by a solemn oath, or as by an oath. That is, It is as sure and fixed as if he had taken an oath. Compare Hebrews 6:13. The "time," so to speak, if the word time can be applied to transactions in a past eternity, was that when he was designated in the divine purpose as Messiah; in the eternal counsels of God. Compare Psalm 2:7.

And will not repent - Will not change his purpose.

Thou art a priest forever after the order of Melchizedek - The word rendered "order" here means properly a word, a thing, a matter; hence, a way or manner. The meaning here is, that he would be a priest "after the manner" of Melchizedek; or, such a priest as he was. He would not be of the tribe of Levi; he would not be in the regular line of the priesthood, but he would resemble, in the characteristics of his office, this ancient priest-king, combining in himself the two functions of priest and king; as a priest, standing alone; not deriving his authority from any line of predecessors; and having no successors. See this verse explained at length, in its application to the Messiah, in the notes at Hebrews 5:6 (note), Hebrews 5:10 (note); Hebrews 7:1-3 (note). The passage as it stands here, and as looked at without any reference to the use made of it in the New Testament, would imply these things:

(1) That he who was spoken of would be, in a proper sense, a priest.

(2) that he would have a perpetual or permanent priesthood - "forever."

(3) that he would not be of the established line of priests in the tribe of Levi, but that his appointment would be unusual and extraordinary.

(4) that the appointment would come directly from God, and would not be "derived" from those who went before him.

(5) that as a priest he would "resemble" Melchizedek, according to the record which was found of Melchizedek in Genesis.

(6) that as Melchizedek was a priest of the Most High God, so he would be.

(7) that as Melchizedek combined in himself the functions of both priest and king, so these would be found in him.

(8) that as Melchizedek had no successors in office, so he would have none.

How far these things were applicable to the Lord Jesus Christ, and with what propriety the passage might be applied to him, may be seen by examining the Epistle to the Hebrews, Hebrews 5-7.

110:4 Sworn - That this priesthood might be made sure and irrevocable.