Deuteronomy 16:9-17 ESV
“You shall count seven weeks. Begin to count the seven weeks from the time the sickle is first put to the standing 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. And 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 towns, the sojourner, the fatherless, and the widow who are among you, at the place that the LORD your God will choose, to make his name dwell there. You shall remember that you were a slave in Egypt; and you shall be careful to observe these statutes. “You shall keep the Feast of Booths seven days, when you have gathered in the produce from your threshing floor and your winepress. You shall rejoice in your feast, you and your son and your daughter, your male servant and your female servant, the Levite, the sojourner, the fatherless, and the widow who are within your towns. For seven days you shall keep the feast to the LORD your God at the place that the LORD will choose, because the LORD your God will bless you in all your produce and in all the work of your hands, so that you will be altogether joyful. “Three times a year all your males shall appear before the LORD your God at the place that he will choose: at the Feast of Unleavened Bread, at the Feast of Weeks, and at the Feast of Booths. They shall not appear before the LORD empty-handed. Every man shall give as he is able, according to the blessing of the LORD your God that he has given you.