Exodus 23:15

¹⁵ Thou shalt keep the feast of unleavened bread: (thou shalt eat unleavened bread seven days, as I commanded thee, in the time appointed of the month Abib; for in it thou camest out from Egypt: and none shall appear before me empty:)

Abel

Abel signifies celestial love, which is loving the Lord. Similarly, he represents good conjoined with truth. (Apocalypse Explained 817).

In Genesis 4:2-9, Abel's offering signifies worship from charity as acceptable by the Lord, while worship from faith alone is not. (Arcana Coelestia 325, 341, Apocalypse Explained 817, Arcana Coelestia 326)

³ And Moses said unto the people, Remember this day, in which ye came out from Egypt, out of the house of bondage; for by strength of hand the LORD brought you out from this place: there shall no leavened bread be eaten.