Jesus said, “You of little faith, why are you talking about having no bread?  Do you still not perceive? Do you not remember the five loaves for the five thousand, and how many baskets you gathered?  Or the seven loaves for the four thousand, and how many baskets you gathered? How could you fail to perceive that I was not speaking about bread? Beware of the yeast of the Pharisees and Sadducees!” Then they understood that he had not told them to beware of the yeast of bread, but of the teaching of the Pharisees and Sadducees.

Matthew 16:8-12