NET Bible
"but Jesus did so with a sworn affirmation by the one who said to him,“The Lord has sworn and will not change his mind,‘You are a priest forever’”–"
— Hebrews 7:21, NET Bible
“(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:)”
“(for they indeed have been made priests without an oath; but he with an oath by him that saith of him, The Lord sware and will not repent himself, Thou art a priest for ever); ”
“(for they indeed have been made priests without an oath), but he with an oath by him that says of him, "The Lord swore and will not change his mind, 'You are a priest forever, according to the order of Melchizedek.'"”
“But this with an oath, by him that said unto him: The Lord hath sworn and he will not repent: Thou art a priest for ever).”
“(For those were made priests without an oath, but this one was made a priest with an oath by him who says of him, The Lord gave his oath, which he will not take back, that you are a priest for ever);”
“(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:)”
On the one hand a former command is set aside because it is weak and useless,
for the law made nothing perfect. On the other hand a better hope is introduced, through which we draw near to God.
And since this was not done without a sworn affirmation– for the others have become priests without a sworn affirmation,
but Jesus did so with a sworn affirmation by the one who said to him,“The Lord has sworn and will not change his mind,‘You are a priest forever’”–
accordingly Jesus has become the guarantee of a better covenant.
And the others who became priests were numerous, because death prevented them from continuing in office,
but he holds his priesthood permanently since he lives forever.