Matthew 5:33-37

33 `Again, ye heard that it was said to the ancients: Thou shalt not swear falsely, but thou shalt pay to the Lord thine oaths;

34 but I -- I say to you, not to swear at all; neither by the heaven, because it is the throne of God,

35 nor by the earth, because it is His footstool, nor by Jerusalem, because it is a city of a great king,

36 nor by thy head mayest thou swear, because thou art not able one hair to make white or black;

37 but let your word be, Yes, Yes, No, No, and that which is more than these is of the evil.