You know, there's a lot of wisdom there. Because if you use something long enough, you tend to assume that it's yours. But everything we have belongs to God. God wants us to remember that. He told Israel that one day they would be richly blessed. But he warned them:
Do not say to yourself, "My power and the might of my own hand have gotten me this wealth." But remember the Lord your God, for it is he who gives you power to get wealth, so that he may confirm his covenant that he swore to your ancestors, as he is doing today. (Deuteronomy 8:17-18).
Think about it. Is it harder to give up something of your own or give someone back what is already his? If I need to haul some stuff around, I might need to borrow a friend's pickup truck for a while. Suppose I kept it for a day. Then I start to give it back to him. Is that hard to do? Here's a car that's worth thousands of dollars and I'm just giving it to him? Sure, it's easy to give it to him because it's not mine; it belongs to my friend.
What we have belongs to God; it's his stuff to begin with! He blesses us by letting us use it, but it's still his. And when we understand that, giving to God becomes a lot easier.
"Offer to God a sacrifice of thanksgiving, and pay your vows to the Most High. Call on me in the day of trouble; I will deliver you, and you shall glorify me" (Psalm 50:14 NRS).