In this passage, our Lord Jesus Christ continues His teaching using parables. When St Peter asked, Jesus interpreted the teaching to help his disciples, and I believe all of us including me, better understand…
“Then the scribes and the Pharisees came to him from Jerusalem, saying: “Why do your disciples transgress the tradition of the elders? For they do not wash their hands when they eat bread.”
But responding, he said to them: “And why do you transgress the commandment of God for the sake of your tradition? For God said: ‘Honor your father and mother,’ and, ‘Whoever will have cursed father or mother shall die a death.’
But you say: ‘If anyone will have said to father or mother, “It is dedicated, so that whatever is from me will benefit you,” then he shall not honor his father or his mother.’
So have you nullified the commandment of God, for the sake of your tradition. Hypocrites!
How well did Isaiah prophesy about you, saying: ‘This people honors me with their lips, but their heart is far from me. For in vain do they worship me, teaching the doctrines and commandments of men.’ ”
And having called the multitudes to him, he said to them: “Listen and understand. A man is not defiled by what enters into the mouth, but by what proceeds from the mouth. This is what defiles a man.”
Then his disciples drew near and said to him, “Do you know that the Pharisees, upon hearing this word, were offended?” But in response he said: “Every plant which has not been planted by my heavenly Father shall be uprooted. Leave them alone. They are blind, and they lead the blind. But if the blind are in charge of the blind, both will fall into the pit.”
And responding, Peter said to him, “Explain this parable to us.” But he said: “Are you, even now, without understanding? Do you not understand that everything that enters into the mouth goes into the gut, and is cast into the sewer?
But what proceeds from the mouth, goes forth from the heart, and those are the things that defile a man. For from the heart go out evil thoughts, murders, adulteries, fornication, thefts, false testimonies, blasphemies. These are the things that defile a man.
But to eat without washing hands does not defile a man.””