1 Corinthians 5:6-8

Revised Standard Version Catholic Edition

⁶ Your boasting is not good. Do you not know that a little leaven leavens the whole lump? ⁷ Cleanse out the old leaven that you may be a new lump, as you really are unleavened. For Christ, our paschal lamb, has been sacrificed. ⁸ Let us, therefore, celebrate the festival, not with the old leaven, the leaven of malice and evil, but with the unleavened bread of sincerity and truth.