Leviticus 23:4-8

These are the set feasts of Jehovah, even holy convocations, which ye shall proclaim in their appointed season. In the first month, on the fourteenth day of the month at even, is Jehovah’s passover. And on the fifteenth day of the same month is the feast of unleavened bread unto Jehovah: seven days ye shall eat unleavened bread. In the first day ye shall have a holy convocation: ye shall do no servile work. But ye shall offer an offering made by fire unto Jehovah seven days: in the seventh day is a holy convocation; ye shall do no servile work.