Matthew 15:1-20; 23:25-28

It's dinner time! As the kids come inside from playing they are told to go wash their hands before dinner. Perhaps your out to eat at a restaurant and after you place your order you go to the restroom to wash your hands. In an attempt to safeguard ourselves from consuming germs we often do these things.
The Pharisees were always concerned about appearance and the exterior. They condemn the disciples for eating with unwashed hands. At this point Jesus uses this opportunity to expose their Pharisaical teaching. We are not defile by what we come into contact with, but rather by what we allow to enter into our hearts. Proverbs tells us to "Keep thy heart with all diligence," because that is the true source of our defilement. Jesus said, "But those things which proceed out of the mouth come forth from the heart; and they defile the man."
In this wicked, evil, sinful world we live in, as much as we try, it is impossible to avoid coming into contact with things that could defile us. So the key is to make sure those things never make it down into our heart. In order to keep our heart clean we must first guard it. Keep watch over what your allowing into your heart. If by chance something sneaks into your heart, God has given us a great cleansing agent called Confession. Confession is spiritually washing your hands. Confession is not informing God our your defilement, He is already aware of that. Confession is cleansing your heart.
Jesus rebuked them..."Woe unto you, scribes and Pharisees, hypocrites! for ye make clean the outside of the cup and of the platter, but within they are full of extortion and excess."  Let's heed Jesus teaching to cleanse first that which is within the cup and platter, that the outside may be clean also.