Hebrews 7:20-22

20And by how much [it was] not without the swearing of an oath;

21(for they are become priests without the swearing of an oath, but he with the swearing of an oath, by him who said, as to him, The Lord has sworn, and will not repent [of it], Thou [art] priest for ever [according to the order of Melchisedec];)

22by so much Jesus became surety of a better covenant.