The Feast of the Passover: Lasted Seven Days
Source: TTT
Exodus 12:15
For seven days you must eat unleavened bread. On the first day you are to remove the leaven from your houses. Whoever eats anything leavened from the first day through the seventh must be cut off from Israel.
Leviticus 23:6
On the fifteenth day of the same month begins the Feast of Unleavened Bread to the LORD. For seven days you must eat unleavened bread.