Deuteronomy 16:9-11

9“You are to count seven weeks, counting the weeks from the time the sickle is first put to the standing grain.

10You are to celebrate the Festival of Weeks to the Lord your God with a freewill offering that you give in proportion to how the Lord your God has blessed you.

11Rejoice before the Lord your God in the place where he chooses to have his name dwell — you, your son and daughter, your male and female slave, the Levite within your city gates, as well as the resident alien, the fatherless, and the widow among you.