Therefore let us keep the feast, not with old yeast, neither with the yeast of malice and wickedness, but with the unleavened bread of sincerity and truth.

How is it that you don't perceive that I didn't speak to you concerning bread? But beware of the yeast of the Pharisees and Sadducees."

Then they understood that he didn't tell them to beware of the yeast of bread, but of the teaching of the Pharisees and Sadducees.