Commentaries:
The Israelite set aside the second tithe throughout the year and consumed it at the annual holy festivals of God for whatever his heart desired. This means that he spent the tithe on things that enhanced his glorifying of God or added joy to the feast.
The same applies to our use of second tithe today. Unlike the use of first tithe, the individual who saves second tithe should use it. God wants His people to enjoy the physical abundance He provides at the feasts as they worship Him and learn to reverence and fear Him in ways that please Him. Because of His blessing, many can also help others observe the feasts.
Martin G. Collins
Tithing: Second Tithe