The chapter also outlines the tithes and makes two points clearly: 1) The tithe was brought in to provide for not only the Levites, who had no other means of support, but also for the widows, the refugee, and the orphan. 2) A portion of the tithe (the firstborn, the grain, the new wine, and the olive oil), were to be eaten in the place God set apart for their worship. Although these were "offered to the Lord," the Lord essentially shared them with those making the offering in a celebration of all that God had provided.
"28At the end of every three years, bring all the tithes of that year’s produce and store it in your towns, 29 so that the Levites (who have no allotment or inheritance of their own) and the foreigners, the fatherless and the widows who live in your towns may come and eat and be satisfied, and so that the Lord your God may bless you in all the work of your hands." (They were not to gather or harvest during the first two years so that the land could remain fallow.)
What if we really understood the connection between giving generously and God blessing all the work of our hands? How often are we tempted by the thought, "I see the need, but I just can't afford to give...." I'll admit, as I've seen the numerous posts admonishing people to give money, not used clothes, old toys, or canned goods, for disaster relief, the thought crept into my mind. It's a lot easier to donate things you don't really need anyway than it is to give money. But God has promised to meet our needs. And I can't recall a single story in the Bible where God admonished someone who gave generously rather than keeping God's provision for themselves.
But I do recall the widow of Zarephath as well as the widow's mites in the New Testament. In both of those instances, widows with no means of support gave the very last of their resources to the Lord - and the Lord provided for them.