“(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:)”
Hebrews 7:21 (KJV)
Context Reading
19For the law made nothing perfect, but the bringing in of a better hope did; by the which we draw nigh unto God. 20And inasmuch as not without an oath he was made priest: 21(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:) 22By so much was Jesus made a surety of a better testament. 23And they truly were many priests, because they were not suffered to continue by reason of death: