'Oath' in the Bible

For men indeed swear by a greater one, and in every dispute of theirs the oath is final for confirmation.

In this way God, being determined to show more abundantly to the heirs of the promise the immutability of his counsel, interposed with an oath;

Inasmuch as he was not made priest without the taking of an oath

(for they indeed have been made priests without an oath), but he with an oath by him that says of him, "The Lord swore and will not change his mind, 'You are a priest forever, according to the order of Melchizedek.'"

For the law appoints men as high priests who have weakness, but the word of the oath which came after the law appoints a Son forever who has been perfected.