1 Corinthians 5:7-8

7Remove the old yeast ⌞of sin⌟ so that you may be a new batch of dough, since you don’t actually have the yeast ⌞of sin⌟. Christ, our Passover lamb, has been sacrificed.

8So we must not celebrate our festival with the old yeast ⌞of sin⌟ or with the yeast of vice and wickedness. Instead, we must celebrate it with the bread of purity and truth that has no yeast.