A little old dough

Thousands of people are crowding in, so close that they trample on one another. Yet Jesus first speaks to his own disciples. Leaven was a bit of old, risen dough that you kneaded into new dough. Before Passover, Jewish families removed all the leaven from the house.

So the warning is for those who stand close to Jesus. Just before, he had sharply criticised religious people. Anyone hearing that quickly feels better about themselves. That is exactly where it begins. A little pretending starts small and works its way through your life unnoticed.