Matthew 16:12
Then they understood that he did not bid them beware of the leaven of bread, but of the teaching of the Pharisees and of the Sadducees.
Luke 12:1
In the mean time, when myriads of the people had come together, so that they trod one upon another, he began to say to his disciples first of all: Beware of the leaven of the Pharisees, which is hypocrisy.
Acts 12:3
And when he saw that it pleased the Jews, he apprehended Peter also. Those were the days of unleavened bread.
1 Corinthians 5:7-8
Purge out the old leaven, that you may be a new mass, as you are without leaven; for Christ, our passover, has been sacrificed for us.
Galatians 5:12
that those who trouble you would even cut themselves off!