For seven days (Nisan 15-22) we are to eat unleavened bread. Allow no hametz (fermented/leavened bread) in our homes or within our borders. The first and seventh days (Nisan 15 and 23) are for resting. No work is allowed except what's required for each person to eat. The day the #passover lamb is killed (Nisan 14) isn't a day of rest or technically even part of the Feast of Unleavened Bread. 1 day + 7. In some ways, this mirrors the eighth day of Sukkot: a 7-day feast + 1 extra day.

Unleavened Bread = 1 + 7 (Pesach, followed by Unleavened Bread)
Tabernacles = 7 + 1 (Sukkot, followed by Shmini Atzaret)

Exodus 12:15-20