Gospel text (Mathew 5,33-37): Jesus said to his disciples, «You have also heard that people were told in the past: Do not break your oath; an oath sworn to the Lord must be kept. But I tell you this: do not take oaths. Do not swear by the heavens, for they are God's throne, nor by the earth, because it is his footstool, nor by Jerusalem because 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. Say yes when you mean yes and say no when you mean no. Anything else you say comes from the devil».