What is the meaning of Hebrews 7:21?

* The two F.O.G. Bibles & Commentary below are currently a work in progress.

but Jesus became a priest with an oath by the One who said to Him: “The Lord has sworn and will not change His mind: ‘You are a priest forever.’”

Berean Standard Bible (BSB)

(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.’”

World English Bible (WEB)

(For{G1063} those priests{G2409} were{G3303}{G1526}{(G5748)} made{G1096}{(G5756)} without{G5565} an oath{G3728}; but{G1161} this with{G3326} an oath{G3728} by{G1223} him that said{G3004}{(G5723)} unto{G4314} him{G846}, The Lord{G2962} sware{G3660}{(G5656)} and{G2532} will{G3338} not{G3756} repent{G3338}{(G5700)}, Thou{G4771} art a priest{G2409} for{G1519} ever{G165} after{G2596} the order{G5010} of Melchisedec{G3198}:)

Strong's King James

(21) because they surely become priests without a vowed oath but He with a vowed oath by The One who said to Him,"יהוה YAHWEH HAS VOWED, YOU'RE A PRIEST INTO THE AGE."

The F.O.G*

[21] But Jesus became priest with an oath when יהוה declared: "יהוה has sworn and will not change His mind: 'You are a priest forever.'"

The F.O.G Paraphrase

and he with an oath through Him who is saying unto him, ‘The Lord sware, and will not repent, Thou art a priest—to the age, according to the order of Melchisedek;’)

Young's Literal Translation