'Oath's' in the Bible

And the king was sorry: nevertheless for the oath's sake, and them which sat with him at meat, he commanded it to be given her.

And the king was exceeding sorry; yet for his oath's sake, and for their sakes which sat with him, he would not reject her.

And so [because of the oath’s greater strength and force] Jesus has become the certain guarantee of a better covenant [a more excellent and more advantageous agreement; one that will never be replaced or annulled].