Matthew 16:12
Then they realized that what he told them to beware of was not leaven but the teaching of the Pharisees and Sadducees.
Luke 12:1
Meanwhile as the crowd was gathering in its thousands till they trod on one another, he proceeded to say to his disciples first of all, "Be on your guard against the leaven of the Pharisees, which is hypocrisy,
Acts 12:3
and when he saw this pleased the Jews, he went on to seize Peter. (This was during the days of unleavened bread.)
1 Corinthians 5:7-8
Clean out the old dough that you may be a fresh lump. For you are free from the old leaven; Christ our paschal lamb has been sacrificed.
Galatians 5:12
O that those who are upsetting you would get themselves castrated!