Matthew 16:11-12

11I spoke to you about the yeast of the Pharisees and the Sadducees. I said that you must not accept it. You should understand now that I was not speaking about bread.’

12Then the disciples understood what Jesus was talking about. They did not need to be careful about the yeast that they used in their bread. Instead, they must be careful about what the Pharisees and Sadducees were teaching. They must not accept it.