Leviticus 23:6-10

Then on the fifteenth day of the same month there 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 laborious work.

But for seven days you shall present an offering by fire to the Lord. On the seventh day is a holy convocation; you shall not do any laborious work.’ ”

Then the Lord spoke to Moses, saying,

“Speak to the sons of Israel and say to them, ‘When you enter the land which I am going to give to you and you gather its harvest, then you shall bring in the sheaf of the first fruits of your harvest to the priest.