Matthew 16:12
Then they understood that He did not bid them beware of the leaven of the bread, but of the teaching of the Pharisees and Sadducees.
Luke 12:1
In the meantime, the vast multitude having been gathered together, so as to tread one upon another, He began to say to His disciples, first, "Beware of the leaven of the Pharisees, which is hypocrisy.
Acts 12:3
and, seeing that it pleased the Jews, he proceeded to seize Peter also. And then were the days of unleavened bread.
1 Corinthians 5:7-8
Purge out the old leaven, that ye may be a new lump, even as ye are unleavened. For our passover was sacrificed, even, Christ;
Galatians 5:12
O that those who are unsettling you would even cut themselves off!