Hebrews 7:19-22

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:) By so much was Jesus made a surety of a better testament.