Hebrews 7:17-21

For he testifieth, Thou art a priest for ever After the order of Melchisedec. For there is verily a disannulling of the commandment going before for the weakness and unprofitableness thereof. For the law made nothing perfect, but the bringing in of a better hope did; by the which we draw nigh unto God. And inasmuch as not without an oath he was made priest: (for those priests were made without an oath; but this with an oath by him that said unto him, The Lord sware and will not repent, Thou art a priest for ever After the order of Melchisedec:)