1 Corinthians 5:6-8 Your glorying is not good. Do you not know that a little leaven leavens the whole lump? Therefore purge out the old leaven, that you may be a new lump, since you truly are unleavened. For indeed Christ, our Passover, was sacrificed for us. Therefore let us keep the feast, not with old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth.
Matthew 16:6 Then Jesus said to them, "Take heed and beware of the leaven of the Pharisees and the Sadducees."
Luke 12:1 In the meantime, when an innumerable multitude of people had gathered together, so that they trampled one another, He began to say to His disciples first of all, "Beware of the leaven of the Pharisees, which is hypocrisy.
Leviticus 2:11 "No grain offering which you bring to the LORD shall be made with leaven, for you shall burn no leaven nor any honey in any offering to the LORD made by fire.
Matthew 16:11-12 How is it you do not understand that I did not speak to you concerning bread?—but to beware of the leaven of the Pharisees and Sadducees." Then they understood that He did not tell them to beware of the leaven of bread, but of the doctrine of the Pharisees and Sadducees.
Mark 8:15 Then He charged them, saying, 'Take heed, beware of the leaven of the Pharisees and the leaven of Herod.'
Leviticus 23:17 You shall bring from your dwellings two wave loaves of two-tenths of an ephah. They shall be of fine flour; they shall be baked with leaven. They are the firstfruits to the LORD.
Deuteronomy 16:3 You shall eat no leavened bread with it; seven days you shall eat unleavened bread with it, that is, the bread of affliction (for you came out of the land of Egypt in haste), that you may remember the day in which you came out of the land of Egypt all the days of your life.