You should not take an oath, [saying] ‘by my head,’ for you cannot make a single hair white or black.
And which one of you can worry yourself into living a single day longer?
nor ‘by earth,’ for it is the footstool for His feet; nor ‘by Jerusalem,’ for it is the city of the great King [i.e., God].
But you should just say ‘yes’ [when you mean] yes, and ‘no’ [when you mean] no. Whatever you say beyond these [i.e., enforcing them by oaths] is of the evil one [i.e., the devil].