1 Corinthians 5:6 - 5:8
6 Your boasting is not good. Do you not know that a little leaven leavens the whole lump? 7 Clean out the old leaven so that you may be a new lump, just as you are in fact unleavened. For Christ, our Passover lamb, also was sacrificed. 8 Therefore let us celebrate the feast, not with old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth.