The mission of the disciples

Jesus said to his disciples: ‘You have learnt how it was said to our ancestors: You must not break your oath, but must fulfil 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 that is the 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 say is “Yes” if you mean yes, “No” if you mean no; anything more than this comes from the evil one.’ (Matthew 5:33-37)