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.'"

Numbers 23:19
God is not a man, that He should lie, or a son of man, that He should change His mind. Does He speak and not act? Does He promise and not fulfill?

1 Samuel 15:29
Moreover, the Glory of Israel does not lie or change His mind, for He is not a man, that He should change His mind."

Psalm 110:4
The LORD has sworn and will not change His mind: "You are a priest forever in the order of Melchizedek."

Romans 11:29
For God's gifts and His call are irrevocable.

Hebrews 5:6
And in another passage God says: "You are a priest forever in the order of Melchizedek."

Hebrews 7:17
For it is testified: "You are a priest forever in the order of Melchizedek."

Hebrews 7:20
And none of this happened without an oath. For others became priests without an oath,

Hebrews 7:23
Now there have been many other priests, since death prevented them from continuing in office.

Hebrews 7:28
For the law appoints as high priests men who are weak; but the oath, which came after the law, appointed the Son, who has been made perfect forever.

(For those priests were made without an oath; but this with an oath by him that said to him, The Lord swore and will not repent, You are a priest for ever after the order of Melchisedec:)