Matthew 16:5-6, 11-12

When the disciples reached the other side of the sea, they realized that they had forgotten to bring bread. Jesus said to them, “Watch out and be on your guard against the leaven of the Pharisees and Sadducees.”

How is it that you fail to understand that I was not talking to you about bread? But 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 [false] teaching of the Pharisees and Sadducees.