'Oath' in the Bible
Whereupon he promised with an oath to give her whatever she should ask.
Again he denied it with an oath, "I don't know the man."
Therefore, being a prophet, and knowing that God had sworn with an oath to him that of the fruit of his body, according to the flesh, he would raise up the Christ to sit on his throne,
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.
But above all things, my brothers, don't swear, neither by heaven, nor by the earth, nor by any other oath; but let your "yes" be "yes," and your "no," "no;" so that you don't fall into hypocrisy.