After that, Pharisees and religion scholars came to Jesus all the way from Jerusalem, criticizing, “Why do your disciples play fast and loose with the rules?” But Jesus put it right back on them. “Why do you use your rules to play fast and loose with God’s commands? God clearly says, ‘Respect your father and mother,’ and, ‘Anyone denouncing father or mother should be killed.’ But you weasel around that by saying, ‘Whoever wants to, can say to father and mother, What I owed to you I’ve given to God.’ That can hardly be called respecting a parent. You cancel God’s command by your rules. Frauds! Isaiah’s prophecy of you hit the bull’s-eye:

These people make a big show of saying the right thing,

    but their heart isn’t in it.

They act like they’re worshiping me,

    but they don’t mean it.

They just use me as a cover

    for teaching whatever suits their fancy.”

He (Jesus) then called the crowd together and said, “Listen and take this to heart. It’s not what you swallow that pollutes your life, but what you vomit up.” (Mat 15:1-11 MSG)

The Pharisees were quick to point out that the disciples had broken the rules that they had laid out for the people.  This is a bit like all the add-ons churches give to new members, or in the past, rules about what to wear or where you could go. Jesus responds by pointing out that the Pharisees don’t break the rules, they twist what the Word of God says to fit themselves.

Jesus quotes Isaiah, pointing out that is not the exterior that counts, it’s the heart that determines who you are and what comes out of a person that determines who you are.