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.

Why is it that you do not understand that I did not speak to you concerning bread? But beware of the yeast of the Pharisees and Sadducees."

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