you have heard that it was said to the men of old, 'You shall not swear
falsely, but shall perform to the Lord what you have sworn.' But I say
to you, Do not swear at all, either by heaven, for it is the throne of
God, or by the earth, for it is his footstool, or by Jerusalem, for it
is the city of the great King. And do not swear by your head, for you
cannot make one hair white or black. Let what you say be simply 'Yes'
or 'No'; anything more than this comes from evil.