The scripture in which the Feast of Unleavened Bread is introduced is in Leviticus 23.

6 "And on the fifteenth day of the same month is the Feast of Unleavened Bread to the Lord; seven days you must eat unleavened bread.
7 And the first day shall be a holy convocation to you: ye shall do no servile work.
8 And ye shall offer whole-burnt-offerings to YHWH seven days; and the seventh day shall be a holy convocation to you: ye shall do no servile work.
9 And YAHUVEH spoke to Moses, saying,
10 Speak to the children of Israel, and thou shalt say to them, When ye shall enter into the land which I give you, and reap the harvest of it, then shall ye bring a sheaf, the first-fruits of your harvest, to the priest;
11 and he shall lift up the sheaf before YHWH, to be accepted for you. On the Morrow of the First Day the Priest shall Lift It Up.
12 And ye shall offer on the day on which ye bring the sheaf, a lamb without blemish of a year old for a whole-burnt-offering to YAHUVEH.
13 And its meal-offering two tenth portions of fine flour mingled with oil: it is a Sacrifice to YAHUVEH, a smell of sweet savour to YAHUVEH, and its drink-offering the fourth part of a hin of wine.
14 And ye shall not eat bread, or the New parched corn, until This Same Day, until ye Offer the Sacrifices to your God: it is a perpetual statute throughout your generations in all your dwellings.
15 And ye shall number to yourselves from the day after the Sabbath, (High Sabbath) from the Day On Which Ye Shall Offer The Sheaf of the Wave Offering, seven full weeks:
16 until the morrow after the last week ye shall number fifty days, and shall bring a new meal-offering to YAHUVEH. " -Lev.23:6-16

The scripture stipulates the duration of the feast. It is to last seven days. The first day, which is on the 15th of the first month (Nisan) and the day following Passover is day #1 of the feast. This first day is a High Sabbath, a sacred assembly, a holy convocation or a high holy day. The seventh day is the 21st day of the first month (Nisan) and is also a High Sabbath, no work is to be done on the High Sabbaths.

The Symbol Of Leaven As Wickedness.

Leaven in the scriptures symbolizes sin.
From the Believers perspective, the picture is quite clear.
YAHUSHUA was the unleavened sinless Bread of Heaven.
His life was one of sinless perfection.
And His body was offered up to YAHUVEH.
He was the acceptable and perfect sacrifice for sin.

The Feast of Unleavened Bread is also a calling to YAH'S consecrated people. They are exhorted to journey on with their Saviour in a walk of holiness. In YAHUSHUA we partake of the unleavened Bread. Through Him we enter into a new state of being. We come into submission to YAHUVEH in unpretentious sincerity and truth.

Here are the words of the Apostle Paul on the matter.

1 Corinthians 5
7. Therefore purge out the old leaven, that you may be a new lump, since you truly are unleavened. For indeed Mashiach, our Passover, was sacrificed for us.
8. Therefore let us keep the feast, not with old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth.

When the Israelites left Egypt they left in haste. The bread they took with them was unleavened bread, baked in haste for a people who were on the move and preparing their victuals to travel. The Feast of Unleavened Bread commemorates the time when the Israelites left Egypt. Their next waypoint was the crossing at the Red Sea. They bread they took with them was not puffed up. It was baked without yeast. There simply was not time enough to allow the bread to rise.

The Bread From Heaven

The Bread from Heaven was seen in the earlier history of Israel. And the heavenly food of provision was spoken of by the prophets. The Bread of Heaven is seen repeatedly in the poetry of the Old Covenant.

Nehemiah 9:15 NKJV
You gave them bread from heaven for their hunger,
And brought them water out of the rock for their thirst,
And told them to go in to possess the land
Which You had sworn to give them.

Psalm 78:24
Had rained down manna on them to eat,
And given them of the bread of heaven.

Psalm 105:40
The people asked, and He brought quail,
And satisfied them with the bread of heaven.

The New Covenant Fulfilment Of The Feast Of Unleavened Bread

The New Covenant fulfillment of the Feast of Unleavened Bread was seen in the Passover of YAHUSHUA'S passion. YAHUSHUA was buried in the earth just in time for the Feast of Unleavened Bread.

The typology of YAHUSHUA as the Bread of Heaven is in the Holy Scriptures. It is taught in the New Testament and in the very words of YAHUSHUA Himself. YAHUSHUA Himself said that He was the "Bread sent from Heaven".

John 6:33 NKJV
"For the bread of YAH is He who comes down from heaven and gives life to the world."

John 6:50
"This is the bread which comes down from heaven, that one may eat of it and not die."

John 6:51
I am the living bread which came down from heaven.
If anyone eats of this bread, he will live forever;
and the bread that I shall give is My flesh,
which I shall give for the life of the world."
The Pharisees, the religious establishment of the time, knew very well what YAHUSHUA was talking about. They were well versed in the typology of the Messiah as the Bread of Heaven. They knew when He referred to Himself as the Bread of Heaven He was claiming to be the promised Messiah, the Holy One of Israel. That is why they took up stones to stone Him.

YAHUSHUA was the final and perfect sacrifice for sin. His body, broken and humbled on the cross, was offered for our redemption. He was buried just as the eve of the Feast of Unleavened Bread approached. He was in the grave for the 15th of Nisan, according to the scriptures. And thus YAHUSHUA HA MASHIACH fulfilled the Feast of Unleavened Bread.