Leviticus 23:6-8

23:6 Then on the fifteenth day of the same month will be the festival of unleavened bread to the Lord; seven days you must eat unleavened bread. 23:7 On the first day there will be a holy assembly for you; you must not do any regular work. 23:8 You must present a gift to the Lord for seven days, and the seventh day is a holy assembly; you must not do any regular work.’”