Deuteronomy 16:8-12

For six days you shall eat unleavened bread, and on the seventh day there shall be a festive assembly to the Lord your God; you shall do no work on it.

“You shall count seven weeks for yourself; you shall begin to count seven weeks from the time you begin to put the sickle to the standing grain.

Then you shall celebrate the Feast of Weeks to the Lord your God with a voluntary offering of your hand in a proportional amount, which you shall give just as the Lord your God blesses you;

and you shall rejoice before the Lord your God, you, your son and your daughter, and your male and female slaves, and the Levite who is in your town, and the stranger, the orphan, and the widow who are in your midst, at the place where the Lord your God chooses to establish His name.

You shall also remember that you were a slave in Egypt, and you shall be careful and comply with these statutes.