'Leaven' in the Bible
Seven days you shall eat unleavened bread, but on the first day you shall remove leaven from your houses; for whoever eats anything leavened from the first day until the seventh day, that person shall be cut off from Israel.
Seven days there shall be no leaven found in your houses; for whoever eats what is leavened, that person shall be cut off from the congregation of Israel, whether he is an alien or a native of the land.
Unleavened bread shall be eaten throughout the seven days; and nothing leavened shall be seen among you, nor shall any leaven be seen among you in all your borders.
‘No grain offering, which you bring to the Lord, shall be made with leaven, for you shall not offer up in smoke any leaven or any honey as an offering by fire to the Lord.
It shall not be baked with leaven. I have given it as their share from My offerings by fire; it is most holy, like the sin offering and the guilt offering.
You shall bring in from your dwelling places two loaves of bread for a wave offering, made of two-tenths of an ephah; they shall be of a fine flour, baked with leaven as first fruits to the Lord.
For seven days no leaven shall be seen with you in all your territory, and none of the flesh which you sacrifice on the evening of the first day shall remain overnight until morning.
He spoke another parable to them, “The kingdom of heaven is like leaven, which a woman took and hid in three pecks of flour until it was all leavened.”
And Jesus said to them, “Watch out and beware of the leaven of the Pharisees and Sadducees.”
How is it that you do not understand that I did not speak to you concerning bread? But beware of the leaven of the Pharisees and Sadducees.”
Then they understood that He did not say to beware of the leaven of bread, but of the teaching of the Pharisees and Sadducees.
And He was giving orders to them, saying, “Watch out! Beware of the leaven of the Pharisees and the leaven of Herod.”
Under these circumstances, after so many thousands of people had gathered together that they were stepping on one another, He began saying to His disciples first of all, “Beware of the leaven of the Pharisees, which is hypocrisy.
It is like leaven, which a woman took and hid in three pecks of flour until it was all leavened.”
Your boasting is not good. Do you not know that a little leaven leavens the whole lump of dough?
Clean out the old leaven so that you may be a new lump, just as you are in fact unleavened. For Christ our Passover also has been sacrificed.
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.