Leviticus 23:3-6

³Six days shall work be done; but on the seventh day is a sabbath of solemn rest, a holy convocation; ye shall do no manner of work; it is a sabbath unto the LORD in all your dwellings.

⁴These are the appointed seasons of the LORD, even holy convocations, which ye shall proclaim in their appointed season.

⁵In the first month, on the fourteenth day of the month at dusk, is the LORD'S passover.

⁶And on the fifteenth day of the same month is the feast of unleavened bread unto the LORD; seven days ye shall eat unleavened bread.