Strongs/TWOT - 7603/2229 - sayor - samek/aleph/resh (yeast or that which sours/ferments) Ex 13:7; Deut 16:4
Strongs/TWOT - 2557/679a -chametz - chet/mem/tzadi-sofit (the action or result of sayor/yeast which produces that which is soured/fermented as in leavened bread - lechem chametz)
The word is used as an extension of soured attitudes in Psalm 73:2. The word is tied to pagan practices and their removal from Hebrew life.
Leaven prohibited with - blood sacrifices, meal offerings, fire offerings - Ex 23:18; 34:25; Lev 2:1; 6:15;.
Leaven permitted with - thank offerings, first fruits offerings - Lev 7:13; Amos 4:5; Lev 23:17.
Leaven in Scripture as a symbol of corruption and impurity - Mt 16:2; Mk 8:15; 1 Cor 5:8.
What is leaven? by Tim O’Hearn
The Jewish definition of leaven, dating from long before the first century, is any of the five biblical grains (and some include rice and corn) which has been exposed to moisture followed by the lapse of a certain period of time before baking in which the introduction of an agent of change may occur. Many rabbis set this time at eighteen minutes. By this definition, a bread made from wheat flour with no yeast added is considered leavened if the dough was mixed and the cook waited, for whatever reason, before baking it. It may even look exactly like unleavened bread, but it is considered leavened. This is also why wine, which is fermented, is able to be used at Passover. It is not made from a grain, so it does not fall under the prohibition against leaven. (Grain alcohols like beer and whiskey, on the other hand, would be prohibited.)
How does this definition help us to understand what leaven represents at Passover, and why it is acceptable at other times? It has to do with what bread represents.
Throughout Jewish history, and particularly since the destruction of the Second Temple, bread has represented the Torah, the word of God (Yeshua) (Deut 8:3; Isa 55:1-4; John 6:35-58). Leaven, then, is grain that has had the opportunity for an outside element to be added and to work to change the grain. It has had time to ferment, if a fermenting agent is nearby. Does the fermenting agent make the grain unfit for consumption? No. Does it change the nature of the grain? Yes. And that is why a time is set aside each year for unleavened bread. Over time it would be easy for the teaching of God’s word, His Torah, to be fermented, changed, adulterated. Once a year God says, “Remember how it was at first. You received my pure law. Go back to the purity of your teaching. Go back to the unleavened bread of My Torah.”
Just as God gave his pure word at Sinai but in the passage of time men added agents of change to that word, so once a year God demands that we return to our roots. Is it because change is bad? No. It is just that we occasionally need a reminder that God brought Israel out with a mighty hand. In doing so, he communicated his word. That is also a part of the Passover.
The reason for the prohibition
Why was leaven originally prohibited? Perhaps if we understand that, we will understand the role leaven plays in our lives.
Years after the event commemorated by Passover, Moses explained, “Thou shalt eat no leavened bread with it; seven days shalt thou eat unleavened bread therewith, even the bread of affliction; for thou camest forth out of the land of Egypt in haste: that thou mayest remember the day when thou camest forth out of the land of Egypt all the days of thy life. (Deut 16:3)” The expressed reason is that they came out of Egypt in haste. How in haste? God told them four days in advance that they were to eat unleavened bread. Why does Moses say it is because it was in haste, if they had four days in which they could have made leavened bread? The answer is found in Ex. 12:34. “And the people took their dough before it was leavened, their kneading troughs being bound up in their clothes upon their shoulders.” Although they had four days to prepare, they immediately packed their kneading troughs. Of all the household goods they packed for the journey, the kneading trough was important enough not to pack last. As a result they had to bake unleavened loaves for four days. Actually, it turned out to be forty years before they needed the kneading troughs, but they could not know that yet.
The “haste” of Israel was not a blind rushing out of Egypt. Instead it was a planned and long awaited exodus. When the time came, the people were so eager to make haste that they packed in advance, and had to do without some things as a result. One of those things was leavened bread. A modern analogy, though imperfect, might be the wife who, preparing for a trip, reminds the family after having done the laundry not to wear anything they plan on taking with them. Other clothes, equally good, have to be worn. For the Israelites, other bread, equally good, had to be eaten.
Every year the Passover is a reminder that God will take His people out of bondage and give them a better land. The unleavened bread does not represent the bondage to sin. Instead it represents the eagerness of the people to leave that bondage. So in prohibiting leavened bread for seven days out of the year, perhaps God is reminding us that we need to set priorities. We need to be packed and ready for our trip to the world to come.
Leaven in the Christian scriptures
I think that if we look at the ways Jesus and Paul, themselves rabbis, used leaven, we will find that even in the first century of the Christian Era leaven did not represent sin, but something entirely different. Jesus even likened the kingdom of heaven to leaven (Matt 13:33; Lk 13:21), which hardly sounds like the totally negative thing many have tried to make it.
Perhaps the best known discourses of Jesus concerning leaven, though, are the times he warns his disciples against “the leaven of the Pharisees,” Sadducees, and Herod (Matt 16:6-12; Mk 8:15-21; Lk 12:1). In the Luke passage he calls it “hypocrisy.” In the Matthew passage, the writer says he was speaking of the “doctrine” of the Pharisees. By doctrine, however, he is not speaking of all the teachings of these holy men. In Matt 22:2-3, Jesus even commands his disciples to follow the teachings of the Pharisees, because the teachings are from Moses. Instead, the leaven of the Pharisees must be those things they do that don’t accord with their teachings. This accords with the idea, previously expressed, that once a year (at least) we need to examine our teachings and bring them back to the unfermented grain of God’s word.
When Paul spoke of leaven, it was always in the context of the Passover. Even in Galatians 5:9, where Pesach is not mentioned, it is the concept that even the minutest amount of leaven makes a loaf unfit for Passover that is expressed.
The other passage where Paul speaks of leaven is 1 Cor 5:1-8. The context is a discussion of the church glorying in one of their own who was living incestuously. In verse 6 he uses the same phrase as in Galatians 5, and in the same way. He continues by saying that Christians should consider every day as Passover, because our lamb has been sacrificed. Therefore, we need to constantly clean house lest any leaven be found. He does talk of the “leaven of malice and wickedness,” but he also speaks of the “old leaven” in a way that implies not that it is sin but any change from the pure word of God.
Why is leaven only prohibited for seven days out of the year? It is obviously not that leaven is in itself sinful. Instead we might as easily ask why Passover was designated to be observed once a year. God knows that man is a forgetful being. So at varying times throughout the year, but especially at Passover, God is telling us in varying ways to remember. Passover, with its unleavened bread and its ceremonies, is but one of God’s reminders that we are not in control.