Deuteronomy 16:16-17

“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.