'Swearing' in the Bible

But he began to invoke a curse [on himself] and to swear [an oath], “I do not know this man you are talking about!”

There were more than forty [men] who formed this plot [and swore this oath].

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

(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;)

For the law constitutes men high priests, having infirmity; but the word of the swearing of the oath which is after the law, a Son perfected for ever.