Matthew 5:33-37

33 "Again you have heard that it was said to them of old time, 'You shall not make false vows, but shall perform to the Lord your vows,'
34 but I tell you, don't swear at all: neither by heaven, for it is the throne of God;
35 nor by the eretz, for it is the footstool of his feet; nor by Yerushalayim, for it is the city of the great King.
36 Neither shall you swear by your head, for you can't make one hair white or black.
37 But let your speech be, 'Yes, yes; No, no.' Whatever is more than these is of the evil one.