Leviticus 23:6-8

On the next day, the fifteenth day of the month, you must begin celebrating the Festival of Unleavened Bread. This festival to the LORD continues for seven days, and during that time the bread you eat must be made without yeast. On the first day of the festival, all the people must stop their ordinary work and observe an official day for holy assembly. For seven days you must present special gifts to the LORD. On the seventh day the people must again stop all their ordinary work to observe an official day for holy assembly.”