Leviticus 23:9-11

Offering the Firstfruits 9The LORD said to Moses, 10“Speak to the Israelites and say to them: ‘When you enter the land I am going to give you and you reap its harvest, bring to the priest a sheaf of the first grain you harvest. 11He is to wave the sheaf before the LORD so it will be accepted on your behalf; the priest is to wave it on the day after the Sabbath.