Teaching about Vows

Matthew 5:33-37

33. Again, you have heard that it was said to our ancestors, You must not break your oath, but you must keep your oaths to the Lord.
34. But I tell you, do not swear an oath at all: either by heaven, for it is God’s throne;
35. or by the earth, for it is his footstool; or by Jerusalem, for it is the city of the Great King.
36. And do not swear by your head, for you cannot make even one hair white or black.
37. All you need to say is simply ‘Yes’ or ‘No’; anything beyond this comes from the evil one.