Long ago our ancestors were oppressed in Egypt until the Most High sent Moses to redeem us by His hand. In the month of Abib, on the 14th day of the month at midnight, Yah sent one last plague on the Egyptians which left all of the first born of the land dead throughout the night. The Most High spared us by the blood of a sacrificed lamb placed on the top and sides of the doors of our houses (Exodus 12). This brought about the first Passover.
Year by year, He commanded the children of Israel to commemorate His deliverance with a celebration starting the sunset of the 14th day of Abib. On this day, we were to sacrifice the Lamb — which was chosen on the 10th day — followed by seven days of eating Unleavened Bread. The 1st and 7th day of the Week of Unleavened Bread are sacred gatherings of rests (high Sabbaths) for saints. The day after the weekly Sabbath, within the Week of Unleavened Bread, is the First Fruit Sheaf Waving. On this day, we would take bundles of the first ripe produce of our crops and offer it to the Most High with the hope that He will give us more produce like it during the time of harvest. (Leviticus 23:1-14)
All of these things are a shadow of the Messiah. He being the Passover Lamb crucified on the 14th of Abib (John 1:36, 1 Peter 1:19), He rested in His tomb on the high Sabbath and the weekly Sabbath then rose the day after the Sabbath — the third day — which was the First Fruit Waving (Leviticus 23:11-12, Matthew 28:1, 1 Corinthians 15:20), and He also taught us to live without leaven in our lives (Luke 12:1).
All this, we observe in the Salvation of Yah offered through the Son.