Hebrews 7:18-22

18 The former regulation is set aside because it was weak and useless 19 (for the law made nothing perfect), and a better hope is introduced, by which we draw near to God.

20 And it was not without an oath! Others became priests without any oath, 21 but he became a priest with an oath when God said to him:

“The Lord has sworn
    and will not change his mind:
    ‘You are a priest forever.’”[b]

22 Because of this oath, Jesus has become the guarantor of a better covenant.

Hebrews 7:15-17

15 And what we have said is even more clear if another priest like Melchizedek appears, 16 one who has become a priest not on the basis of a regulation as to his ancestry but on the basis of the power of an indestructible life. 17 For it is declared:“You are a priest forever,
    in the order of Melchizedek.”

Hebrews 7:11-14

11 If perfection could have been attained through the Levitical priesthood—and indeed the law given to the people established that priesthood—why was there still need for another priest to come, one in the order of Melchizedek, not in the order of Aaron? 12 For when the priesthood is changed, the law must be changed also. 13 He of whom these things are said belonged to a different tribe, and no one from that tribe has ever served at the altar. 14 For it is clear that our Lord descended from Judah, and in regard to that tribe Moses said nothing about priests.

Hebrews 7:5-10

Now the law requires the descendants of Levi who become priests to collect a tenth from the people—that is, from their fellow Israelites—even though they also are descended from Abraham. This man, however, did not trace his descent from Levi, yet he collected a tenth from Abraham and blessed him who had the promises. And without doubt the lesser is blessed by the greater. In the one case, the tenth is collected by people who die; but in the other case, by him who is declared to be living. One might even say that Levi, who collects the tenth, paid the tenth through Abraham, 10 because when Melchizedek met Abraham, Levi was still in the body of his ancestor.

Hebrews 7:1-4

This Melchizedek was king of Salem and priest of God Most High. He met Abraham returning from the defeat of the kings and blessed him, and Abraham gave him a tenth of everything. First, the name Melchizedek means “king of righteousness”; then also, “king of Salem” means “king of peace.” Without father or mother, without genealogy, without beginning of days or end of life, resembling the Son of God, he remains a priest forever.

Just think how great he was: Even the patriarch Abraham gave him a tenth of the plunder!

Hebrews 6:17-20

17 Because God wanted to make the unchanging nature of his purpose very clear to the heirs of what was promised, he confirmed it with an oath. 18 God did this so that, by two unchangeable things in which it is impossible for God to lie, we who have fled to take hold of the hope set before us may be greatly encouraged. 19 We have this hope as an anchor for the soul, firm and secure. It enters the inner sanctuary behind the curtain, 20 where our forerunner, Jesus, has entered on our behalf. He has become a high priest forever, in the order of Melchizedek.

Hebrews 6:13-16

13 When God made his promise to Abraham, since there was no one greater for him to swear by, he swore by himself, 14 saying, “I will surely bless you and give you many descendants.”[d] 15 And so after waiting patiently, Abraham received what was promised.

16 People swear by someone greater than themselves, and the oath confirms what is said and puts an end to all argument.