Matthew 16:12
Then they understood that he had told them to be on their guard, not against the leaven of bread, but against the teaching of the Pharisees and Sadducees.
Luke 12:1
Meanwhile the people had gathered in thousands, so that they trod upon one another, when Jesus, addressing himself to his disciples, began by saying to them: "Be on your guard against the leaven--that is, the hypocrisy--of the Pharisees.
Acts 12:3
And, when he saw that the Jews were pleased with this, he proceeded to arrest Peter also. (This was during the Festival of the Unleavened Bread.)
1 Corinthians 5:7-8
Get rid entirely of the old leaven, so that you may be like new dough-free from leaven, as in truth you are. For our Passover Lamb is already sacrificed-Christ himself;
Galatians 5:12
I could even wish that the people who are unsettling you would go further still and mutilate themselves.