1 Corinthians 5:7-8

Take out all the old yeast so that you will be a new batch of dough without yeast, which you really are. For Christ, our Passover lamb, has been sacrificed. So let us celebrate this feast, but not with the bread that has the old yeast—the yeast of sin and wickedness. Let us celebrate this feast with the bread that has no yeast—the bread of goodness and truth.