Definition and Significance:
Eating unleavened bread is a practice deeply rooted in biblical tradition, primarily associated with the observance of the Passover and the Feast of Unleavened Bread. Unleavened bread, known as "matzah" in Hebrew, is bread made without yeast or any leavening agent, symbolizing purity and the haste with which the Israelites left Egypt.

Biblical Origins:
The command to eat unleavened bread is first found in the Book of Exodus, where God instructs the Israelites to observe the Passover. In Exodus 12:15 , it is written, "For seven days you must eat unleavened bread. On the first day, you are to remove the leaven from your houses. Whoever eats anything leavened from the first day through the seventh must be cut off from Israel." This command is reiterated in Exodus 12:17-20, emphasizing the importance of this practice as a perpetual ordinance.

Symbolism:
Unleavened bread holds significant symbolic meaning in the biblical narrative. It represents the Israelites' swift departure from Egypt, as they did not have time to let their bread rise. This is highlighted in Exodus 12:39 : "They baked unleavened cakes of the dough that they had brought out of Egypt, for it was without yeast; because they had been driven out of Egypt and could not delay, they had not prepared any provisions for themselves."

Furthermore, unleavened bread symbolizes purity and separation from sin. Leaven, or yeast, is often used in Scripture as a metaphor for sin and corruption. In 1 Corinthians 5:7-8 , the Apostle Paul draws on this imagery: "Get rid of the old leaven, that you may be a new unleavened batch, as you really are. For Christ, our Passover lamb, has been sacrificed. Therefore let us keep the feast, not with the old leaven, the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth."

Observance in Jewish Tradition:
The Feast of Unleavened Bread, which immediately follows Passover, is a seven-day festival during which no leavened bread is consumed. This observance is detailed in Leviticus 23:6-8 : "On the fifteenth day of the same month is the Feast of Unleavened Bread to the LORD. For seven days you must eat unleavened bread. On the first day, you are to hold a sacred assembly; you are not to do any regular work. For seven days you are to present an offering made by fire to the LORD. On the seventh day, there shall be a sacred assembly; you must not do any regular work."

Christian Interpretation:
In Christian theology, the practice of eating unleavened bread during the Passover is seen as a foreshadowing of Christ's sacrifice. Jesus, during the Last Supper, which was a Passover meal, broke unleavened bread and shared it with His disciples, instituting the Lord's Supper. In Matthew 26:26 , it is recorded, "While they were eating, Jesus took bread, spoke a blessing and broke it, and gave it to the disciples, saying, 'Take and eat; this is My body.'"

Conclusion:
The practice of eating unleavened bread is a rich tradition that carries deep historical, symbolic, and theological significance. It serves as a reminder of God's deliverance, the call to holiness, and the ultimate sacrifice of Jesus Christ, the true Passover Lamb.