DO NOT SWEAR

St. Anthony 

Jesus said to his disciples: 'You have learnt how it was said to our
ancestors:

You must not break your oath, but must fulfile your
oaths to the Lord.

But I say this to you:

Do not swear at all, either by heaven, since that is God's throne;
or by the earth, since that is his footstool, or by Jerusalem, since
tht is the great city of the great king.

Do not swear by your own head either, since you cannot turn a single hair white or black.

All you need to say is "Yes" if you mean yes, "No" if you mean no;
anything more that this comes from the evil one'.   Mass Readings