The disciples didn't understand, so they asked him privately, when they were back in the house at Capernaum. Jewish people at that time were confused about this notion of ceremonial righteousness.
Are you a young person, still in your teens, early twenties? Let the Saviour give you a glimpse of your heart. Maybe you never thought of it like this. You've got so many sins in there, waiting for expression. Many of them have never been fully expressed yet. You're looking forward to adult life, developing your career. ‘I am going to do well’, you hope. ‘I'm going to get a good job, and earn good money, make a good marriage, have a happy life.’ You have no idea what sins you are going to commit, what's coming up from within, from that infestation which is within. How much we all need the Saviour as early as possible in life. We need to be renewed, and sin’s power is broken. We need to be so changed, that sin doesn't have to have the dominion over us.