'Leaven' in the Bible
Another parable spake he unto them; The kingdom of heaven is like unto leaven, which a woman took, and hid in three measures of meal, till it was all leavened.
And Jesus said unto them, Take heed and beware of the leaven of the Pharisees and Sadducees.
How is it that ye do not perceive that I spake not to you concerning bread? But beware of the leaven of the Pharisees and Sadducees.
Then understood they that he bade them not beware of the leaven of bread, but of the teaching of the Pharisees and Sadducees.
And he charged them, saying, Take heed, beware of the leaven of the Pharisees and the leaven of Herod.
In the mean time, when the many thousands of the multitude were gathered together, insomuch that they trod one upon another, he began to say unto his disciples first of all, Beware ye of the leaven of the Pharisees, which is hypocrisy.
It is like unto leaven, which a woman took and hid in three measures of meal, till it was all leavened.
Your glorying is not good. Know ye not that a little leaven leaveneth the whole lump?
Purge out the old leaven, that ye may be a new lump, even as ye are unleavened. For our passover also hath been sacrificed, even Christ:
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.