Leviticus 23:5-11

5In the first month, on the fourteenth day of the month at twilight, is the Lord's Passover.

6And on the fifteenth day of the same month is the Feast of Unleavened Bread to the Lord; for seven days you shall eat unleavened bread.

7On the first day you shall have a holy convocation; you shall not do any ordinary work.

8But you shall present a food offering to the Lord for seven days. On the seventh day is a holy convocation; you shall not do any ordinary work."

9And the Lord spoke to Moses, saying,

10"Speak to the people of Israel and say to them, When you come into the land that I give you and reap its harvest, you shall bring the sheaf of the firstfruits of your harvest to the priest,

11and he shall wave the sheaf before the Lord, so that you may be accepted. On the day after the Sabbath the priest shall wave it.