Leviticus 23:6-8

And on the fifteenth day of the same month is the Feast of Unleavened Bread to the LORD; for seven days you shall eat unleavened bread. On the first day you shall have a holy convocation; you shall not do any ordinary work. But you shall present a food offering to the LORD for seven days. On the seventh day is a holy convocation; you shall not do any ordinary work.”