Leviticus 23:10-12

10“Speak to the Israelites and tell them: When you enter the land I am giving you and reap its harvest, you are to bring the first sheaf of your harvest to the priest.

11He will present the sheaf before the Lord so that you may be accepted; the priest is to present it on the day after the Sabbath.

12On the day you present the sheaf, you are to offer a year-old male lamb without blemish as a burnt offering to the Lord.