'Leaven' in the Bible
Seven days shall ye eat unleavened bread; even the first day ye shall put away leaven out of your houses: for whosoever eateth leavened bread from the first day until the seventh day, that soul shall be cut off from Israel.
Seven days shall there be no leaven found in your houses: for whosoever eateth that which is leavened, that soul shall be cut off from the congregation of Israel, whether he be a sojourner, or one that is born in the land.
Unleavened bread shall be eaten throughout the seven days; and there shall no leavened bread be seen with thee, neither shall there be leaven seen with thee, in all thy borders.
No meal-offering, which ye shall offer unto Jehovah, shall be made with leaven; for ye shall burn no leaven, nor any honey, as an offering made by fire unto Jehovah.
And that which is left thereof shall Aaron and his sons eat: it shall be eaten without leaven in a holy place; in the court of the tent of meeting they shall eat it.
It shall not be baken with leaven. I have given it as their portion of my offerings made by fire; it is most holy, as the sin-offering, and as the trespass-offering.
And Moses spake unto Aaron, and unto Eleazar and unto Ithamar, his sons that were left, Take the meal-offering that remaineth of the offerings of Jehovah made by fire, and eat it without leaven beside the altar; for it is most holy;
Ye shall bring out of your habitations two wave-loaves of two tenth parts of an ephah : they shall be of fine flour, they shall be baken with leaven, for first-fruits unto Jehovah.
And there shall be no leaven seen with thee in all thy borders seven days; neither shall any of the flesh, which thou sacrificest the first day at even, remain all night until the morning.
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.