'Sarcasm' has nothing to do with it, IMO.
Originally Posted by fracturedInfinity
The context of that verse is in regards to swearing oaths.
Swearing is neither necessary nor desirable when a simple 'yes or no' can be taken at face value.
"Again, you have heard that the ancients were told, 'YOU SHALL NOT MAKE FALSE VOWS, BUT SHALL FULFILL YOUR VOWS TO THE LORD.' "But I say to you, make no oath at all, either by heaven, for it is the throne of God, or by the earth, for it is the footstool of His feet, or by Jerusalem, for it is THE CITY OF THE GREAT KING. "Nor shall you make an oath by your head, for you cannot make one hair white or black. "But let your statement be, 'Yes, yes' or 'No, no'; anything beyond these is of evil.