Leviticus 23:4-8

‘These are the appointed times of the LORD, holy convocations which you shall proclaim at their appointed times: The LORD’S Passover is on the fourteenth day of the first month at twilight. The Feast of Unleavened Bread to the LORD is on the fifteenth day of the same month; for seven days you shall eat unleavened bread. [1 Cor 5:7, 8] On the first day you shall have a holy convocation (calling together); you shall not do any laborious work [on that day]. But you shall present an offering by fire to the LORD for seven days; on the seventh day there shall be a holy convocation; you shall not do any laborious work [on that day].’ ”