Matthew 5:34-37

But now I tell you: do not use any vow when you make a promise. Do not swear by heaven, for it is God's throne; nor by earth, for it is the resting place for his feet; nor by Jerusalem, for it is the city of the great King. Do not even swear by your head, because you cannot make a single hair white or black. Just say ‘Yes’ or ‘No’ — anything else you say comes from the Evil One.