Oaths: Custom of Swearing by the Life of the King
Source: TTT
Genesis 42:15, 16
And this is how you will be tested: As surely as Pharaoh lives, you shall not leave this place unless your youngest brother comes here. / Send one of your number to get your brother; the rest of you will be confined so that the truth of your words may be tested. If they are untrue, then as surely as Pharaoh lives, you are spies!”