Arcana Coelestia #7886
7886. 'You shall eat unleavened bread' means purification from falsities. This is clear from the meaning of unleavened bread' as purification from falsities, dealt with in 2342.
Deuteronomy 16:3-4
3
You shall eat no leavened bread with it. You shall eat unleavened bread with it seven days, even the bread of affliction; for you came forth out of the land of Egypt in haste: that you may remember the day when you came forth out of the land of Egypt all the days of your life.
4
No yeast shall be seen with you in all your borders seven days; neither shall any of the flesh, which you sacrifice the first day at evening, remain all night until the morning.