Six days
Exodus 12:15,16 Seven days shall you eat unleavened bread; even the first day you shall put away leaven out of your houses...
Exodus 13:7,8 Unleavened bread shall be eaten seven days; and there shall no leavened bread be seen with you...
Leviticus 23:6-8 And on the fifteenth day of the same month is the feast of unleavened bread to the LORD: seven days you must eat unleavened bread...
Numbers 28:17-19 And in the fifteenth day of this month is the feast: seven days shall unleavened bread be eaten...
solemn assembly [heb] restraint
Leviticus 23:36 Seven days you shall offer an offering made by fire to the LORD: on the eighth day shall be an holy convocation to you...
2 Chronicles 7:9 And in the eighth day they made a solemn assembly: for they kept the dedication of the altar seven days, and the feast seven days.
Nehemiah 8:18 Also day by day, from the first day to the last day, he read in the book of the law of God. And they kept the feast seven days...
Joel 1:14 Sanctify you a fast, call a solemn assembly, gather the elders and all the inhabitants of the land into the house of the LORD your God...