1 Corinthians 5:6-8

Young's Literal Translation

⁶ Not good [is] your glorying; have ye not known that a little leaven the whole lump doth leaven?

⁷ cleanse out, therefore, the old leaven, that ye may be a new lump, according as ye are unleavened, for also our passover for us was sacrificed -- Christ,

⁸ so that we may keep the feast, not with old leaven, nor with the leaven of evil and wickedness, but with unleavened food of sincerity and truth.