'Take an Oath' in the Bible

the king summoned Shimei and said to him, "You will recall that I made you take an oath by the Lord, and I solemnly warned you, 'If you ever leave and go anywhere, know for sure that you will certainly die.' You said to me, 'The proposal is acceptable; I agree to it.'

So Ezra got up and made the leading priests and Levites and all Israel take an oath to carry out this plan. And they all took a solemn oath.

You must be truthful, honest and upright when you take an oath saying, 'As surely as the Lord lives!' If you do, the nations will pray to be as blessed by him as you are and will make him the object of their boasting."

Do not take an oath by your head, because you are not able to make one hair white or black.