Hebrews 7:21
(for the others indeed without an oath were made priests, but this one with an oath by him that said unto him, The Lord swore and will not repent, Thou art a priest for ever after the order of Melchisedec);
Psalm 110:4
The LORD has sworn and will not repent, Thou art a priest for ever after the order of Melchizedek.
Hebrews 7:17
for the testimony is of this manner, Thou art a priest for ever after the order of Melchisedec.
1 Samuel 15:29
And also the Overcomer of Israel will not lie nor repent concerning this, for he is not a man, that he should repent.
Hebrews 6:16-18
For men verily swear by the greater, and an oath for confirmation is to them an end of all controversy.