1 Corinthians 5:7-8

CAB(i) 7 Purge out the old leaven, in order that you may be a new batch of dough, since you are unleavened. For indeed Christ, our Passover, was sacrificed for us. 8 So then let us observe the feast, not with old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth.