Deuteronomy 16:10-17

Then celebrate the Festival of Harvest to honor the LORD your God. Bring him a voluntary offering in proportion to the blessings you have received from him. This is a time to celebrate before the LORD your God at the designated place of worship he will choose for his name to be honored. Celebrate with your sons and daughters, your male and female servants, the Levites from your towns, and the foreigners, orphans, and widows who live among you. Remember that you were once slaves in Egypt, so be careful to obey all these decrees. “You must observe the Festival of Shelters for seven days at the end of the harvest season, after the grain has been threshed and the grapes have been pressed. This festival will be a happy time of celebrating with your sons and daughters, your male and female servants, and the Levites, foreigners, orphans, and widows from your towns. For seven days you must celebrate this festival to honor the LORD your God at the place he chooses, for it is he who blesses you with bountiful harvests and gives you success in all your work. This festival will be a time of great joy for all. “Each year every man in Israel must celebrate these three festivals: the Festival of Unleavened Bread, the Festival of Harvest, and the Festival of Shelters. On each of these occasions, all men must appear before the LORD your God at the place he chooses, but they must not appear before the LORD without a gift for him. All must give as they are able, according to the blessings given to them by the LORD your God.