Matthew 16:6, 11-12

Jesus said to them, “Watch and beware of the leaven of the Pharisees and Sadducees.”

How is it that you fail to understand that I did not speak about bread? Beware of the leaven of the Pharisees and Sadducees.” Then they understood that he did not tell them to beware of the leaven of bread, but of the teaching of the Pharisees and Sadducees.