'Ferment' in the Bible

When my heart was embitteredAnd I was pierced within [as with the fang of an adder],

Jesus said to them, “Watch out and be on your guard against the leaven of the Pharisees and Sadducees.”

How is it that you fail to understand that I was not talking to you about bread? But beware of the leaven of the Pharisees and Sadducees.”

In the meantime, after so many thousands of the people had gathered that they were stepping on one another, Jesus began speaking first of all to His disciples, “Be continually on your guard against the leaven of the Pharisees [that is, their pervasive, corrupting influence and teaching], which is hypocrisy [producing self-righteousness].

Now while they were trying to kill him, word came to the commander of the [Roman] garrison that all Jerusalem was in a state of upheaval.

Your boasting [over the supposed spirituality of your church] is not good [indeed, it is vulgar and inappropriate]. Do you not know that [just] a little leaven ferments the whole batch [of dough, just as a little sin corrupts a person or an entire church]?