Deuteronomy 16:9-12

“You shall count seven weeks for yourself; begin to count the seven weeks from the time you begin to put the sickle to the grain. Then you shall keep the Feast of Weeks to the LORD your God with the tribute of a freewill offering from your hand, which you shall give as the LORD your God blesses you. You shall rejoice before the LORD your God, you and your son and your daughter, your male servant and your female servant, the Levite who is within your gates, the stranger and the fatherless and the widow who are among you, at the place where the LORD your God chooses to make His name abide. And you shall remember that you were a slave in Egypt, and you shall be careful to observe these statutes.