Leviticus 23:6 On the fifteenth day of the same month is the feast of unleavened bread to Yahweh. Seven days you shall eat unleavened bread. 7 In the first day you shall have a holy convocation. You shall do no regular work. 8 But you shall offer an offering made by fire to Yahweh seven days. In the seventh day is a holy convocation. You shall do no regular work.’”
Immediately after the Angel of Death visited judgment on the homes that were not covered in the saving blood of the lamb, Egypt set the Israelite slaves free. Leaving in great haste they had no time bake bread for the journey. Instead, they made unleavened bread, that is, bread without yeast, gathered their belongings and left Egypt. Of course this Old Covenant festival looked forward to Christ who declared that he is the bread of life, John 6:35, because he alone offers forgiveness of sins and nourishes men’s souls.
He saved them from the hand of the foe;
from the hand of the enemy he redeemed them. Psalm 106:10