Imagine the scene. Knowing that He would soon suffer and die as the Passover Lamb, Jesus commanded His disciples to prepare for this special meal. Jesus wanted to eat the Passover lamb with His disciples before He became the Passover Lamb (Luke 22:15).
The Scriptures tell us that following the Passover meal they sang a hymn, and then went to the Mount of Olives, Matthew 26:30. Great Hallel has been sung by Jews down through the centuries as they have celebrated the Passover? Psalm 118 : 22-24.
Redemption comes first, then the festival of unleavened bread follows. Redemption gives us the ability through the spirit of God to say no to sin (to live unleavened bread).
Leaven swells up, it is anonymous with pride. If we truly understand the lords passover, and receive Him in our heart.
Having personal experience with Messiah, the fruit of it is humility.