What does Mark 7:9 mean?
The words Jesus use here illustrate the natural progression from Mark 7:8. "Reject" is from the Greek root word atheteo. Where "leave" means they disassociate themselves from God's law, "reject" means they deny its validity. "Establish" is from the Greek root word tereo which goes beyond mastering the tradition and into guarding and keeping what already exists.In this, the Jewish leaders are successful. By the third century AD, devout Jews consider eating with unwashed hands equivalent to sleeping with a prostitute; for example, see the Babylonian Talmud, Seder Nashim, Tractate Sotah 4b. In making a law that purports to keep followers ceremonially clean, the scribes manage to show their own arrogance and disrespect God's law.
Their attitude towards God's commandments is in stark contrast with King David's. The longest chapter in the Bible, Psalm 119, is David's declaration of devotion to God's law. David has no wish to add to the law, but to keep it. He sees that the law brings life and requires his heart and soul. But he also knows that when he sins against that law, the answer isn't more laws, but God's grace. He knows God will heal him (Psalm 41:4) and make him clean (Psalm 51:4–7). Over a thousand years before the Pharisees and scribes condemn Jesus' disciples for making themselves unclean by eating with unwashed hands, David writes that it is only God who can make our hearts clean (Psalm 51:10).