Hebrews 7:16-21 NIV

[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.” [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.’ ”