American Standard Version (ASV):
wherefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth.
King James Version (KJV):
Therefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness; but with the unleavened [bread] of sincerity and truth.