Thou art a priest forever, etc. It is on the single word forever, that the Apostle lays stress in this passage; for he confirms what he said of an indissoluble life. He then shows that Christ differs from the whole race of Levi, because he is made a priest for ever. [1] But here it may be objected, as the Jews also do, that the word,lvlm laoulam, does not always mean eternity, but the extent of one age, or, at farthest, a long time; and it is added, that when Moses speaks of the ancient sacrifices, he often uses this expression, "This ordinance shall be forever." (Exodus 12:17, and 19:9.) To this I answer that whenever the sacrifices of the Law are mentioned, "forever" is to be confined to the time of the Law; nor ought this to be deemed strange; for by the coming of Christ a certain renovation of the world was effected. Whenever, then, Moses speaks of his own ministration, he extends the longest time no farther than to Christ. It must yet be also observed, that "forever" is applied to the ancient sacrifices, not with regard to the external ceremony, but on account of their mystical signification. On the present occasion, however, this reason ought to be sufficient, that Moses and his ministrations were for ever; that is, until the coming of the kingdom of Christ, under whom the world was renovated. Now when Christ is come, and a perpetual priesthood is given to him, we can find no end to his age, so that it cannot terminate after a certain period of time. So when applied to him, the word ought to be understood in the sense of eternity; for by the context we are always to judge of the meaning of the word, lvlmlaoulam

Footnotes

1 - This paragraph extends from the 11th verse to the end of the 17th. The "law" parenthetically referred to in the 11th, seems not to be the Mosaic Law generally, as too commonly supposed, but the law respecting the Levitical priesthood, as it appears evident from the 12th and the following verses, for what is spoken of is Christ as being a priest not in succession from Aaron, but according to the order of Melchisedec. See [28]Appendix A 2. -- Ed.

For he testifieth - "That this is the true account of it is proved by the testimony of God himself, that he was to be a priest for ever;" see the note on Hebrews 5:6.

For he testifieth - That is, either the Scripture, in the place so often quoted, or God by that Scripture.
Thou art a priest for ever - This is the proof that he was not appointed according to the carnal commandment, but according to the power of an endless life, because he is a priest for ever; i.e. one that never dies, and is never disabled from performing the important functions of his office; for if he be a priest for ever, he ever lives.

For he testifieth,.... That is, either David, the penman of the psalm, or rather the Holy Ghost, the enditer of it, or God in the Scripture, in Psalm 110:4 of this form of citing Scripture; see Gill on Hebrews 2:6.
thou art a priest for ever after the order of Melchisedec; see Hebrews 5:6.

For--proving His life to be "endless" or indissoluble (Hebrews 7:16). The emphasis is on "for ever." The oldest manuscripts read, "He is testified of, that Thou art," &c.