Repent. Not that He can ever do so, or give way to error: but the sacred writer expresses himself thus, to give us the greatest security. (Calmet)

The order. Hebrew dibrathi, “my order,” Melchisedech. The i has been perhaps designedly inserted, to render the argumentation in the epistle to the Hebrews of no weight, “as the force of the text sinks into just nothing.” (Kennicott)

Protestants and Pagnin here abandon the Hebrew. But Montanus corrects the latter, and substitutes “upon my word,” which is more honest, as he deemed the Hebrew text unerring, though here it be not so unquestionably, as the Almighty would thus address Melchisedech, unless that title be here given to Christ. St. Jerome takes no notice of my, no more than the apostle, &c. (Haydock)

This instance “may perhaps put all serious Christians upon deliberating---whether they should any longer maintain the absolute integrity of the present Hebrew text.” See Psalm xv. 10. (Kennicott, Dis. i. p. 219.)

Melchisedech. Christ is declared king and priest for ever, (Worthington) like Melchisedech, who united in his person both dignities, and presided not over a particular people, nor stood in need of any stated place. His succession is not recorded, and his sacrifice consisted of bread and wine; in all which respects he differed from the Levitical priests, and prefigured Christ, who is immolated under the same species throughout the world, Malachias i. 11. (Menochius)

We read in Scripture of three orders of priesthood: 1st, of kings, 2d, of the first-born, and 3d, of Aaron. Melchisedech, in quality of king, exercised the priestly office, as both functions were formerly united: and hence the word Cohen signifies both a temporal and spiritual prince. This light of nations ensured to his order a perpetual duration, while that of Aaron was to have an end. Thus Christ offered to his Father from all eternity the sacrifice of his obedience, and future sufferings; and in time, he presented that of his own life, which he continues to offer in the Catholic Church, (Calmet) by priests who are only his ministers, 1 Corinthians iv. (Worthington)

The apostle does not specify the oblation of bread and wine, as it was unnecessary, the sacrifice of Christ on the cross having put an end to the sacrifices of the old law, which could only be offered by the children of Aaron, from whom he did not spring. This was enough for his purpose. But as Melchisedech offered bread and wine, Christ must also have done the same, to be of his order. St. Cyprian, and the other Fathers, with great unanimity observe, that the sacrifice of Melchisedech was a figure of that of Jesus Christ, in bread and wine; and of course (Berthier) our sacred mysteries must contain the substance. (Haydock)

By their application, Christ still pacifies his Father in behalf of sinners: so that the effects of his priesthood do not cease, as those of all the priests in the Old Testament did by their death. (Worthington)