15 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. 16 "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. 17 Every man shall give as he is able, according to the blessing of the Lord your God that he has given you.

Matthew Henry's Commentary on Deuteronomy 16:15-17

Commentary on Deuteronomy 16:1-17

(Read Deuteronomy 16:1-17)

The laws for the three yearly feasts are here repeated; that of the Passover, that of the Pentecost, that of Tabernacles; and the general law concerning the people's attendance. Never should a believer forget his low estate of guilt and misery, his deliverance, and the price it cost the Redeemer; that gratitude and joy in the Lord may be mingled with sorrow for sin, and patience under the tribulations in his way to the kingdom of heaven. They must rejoice in their receivings from God, and in their returns of service and sacrifice to him; our duty must be our delight, as well as our enjoyment. If those who were under the law must rejoice before God, much more we that are under the grace of the gospel; which makes it our duty to rejoice evermore, to rejoice in the Lord always. When we rejoice in God ourselves, we should do what we can to assist others also to rejoice in him, by comforting the mourners, and supplying those who are in want. All who make God their joy, may rejoice in hope, for He is faithful that has promised.