King James Version (KJV) Authorized Version 1611
Read Full Chapter (Hebrews 7)

Hebrews 7:17-21 KJV

"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 in asmuch 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:)"
Hebrews Chapter 7, Verse 17-21

Hebrews 7:17-21 in Context (Verses 14–24 KJV)

14
For it is evident that our Lord sprang out of Juda; of which tribe Moses spake nothing concerning priesthood.
15
And it is yet far more evident: for that after the similitude of Melchisedec there ariseth another priest,
16
Who is made, not after the law of a carnal commandment, but after the power of an endless life.
17
For he testifieth, Thou art a priest for ever after the order of Melchisedec.
18
For there is verily a disannulling of the commandment going before for the weakness and unprofitableness thereof.
19
For the law made nothing perfect, but the bringing in of a better hope did; by the which we draw nigh unto God.
20
And 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:)
22
By so much was Jesus made a surety of a better testament.
23
And they truly were many priests, because they were not suffered to continue by reason of death:
24
But this man, because he continueth ever, hath an unchangeable priesthood.