Hebrews 7:20-22

7:20 And since this was not done without a sworn affirmation – for the others have become priests without a sworn affirmation, 7:21 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’” – 7:22 accordingly Jesus has become the guarantee of a better covenant.