'Beware of the Leaven' in the Bible

Then Jesus said unto them, Take heed and beware of the leaven of the Pharisees and of the Sadducees.

How is it that ye do not understand that I spake it not to you concerning bread, that ye should beware of the leaven of the Pharisees and of the Sadducees?

Then understood they how that he bade them not beware of the leaven of bread, but of the doctrine of the Pharisees and of the Sadducees.

And he charged them, saying, Take heed, beware of the leaven of the Pharisees, and of the leaven of Herod.

In those times, the myriads of the crowd being gathered together, so that they trod one on another, he began to say to his disciples first, Beware of the leaven of the Pharisees, which is hypocrisy;