Parshas Bechukosai: The Vilna Gaon Gives The Wealthy Man An Accounting Lesson
"V'Haya Erkicha... BShekel HaKodesh" (Bichukosai 27:3). The Vilna Gaon once paid a visit to a wealthy man to collect money for a Tzedaka cause. The Gvir asked the Vilna Gaon, "Tell me, is it permissible to give tzedaka from other peoples money? I am swimming in debt from all the property and belongings I acquired." In the meantime there was a knock on the door and the tailor entered, delivering a very expensive garment that the Gvir had ordered. The Vilna Gaon asked the Gvir, "and how can you buy such an expensive garment with other peoples money?" The Gvir answered that he didn't pay with anyone else's money. He bought it on credit!
The Vilna Gaon said now I understand the Pasuk in Yirmiya (9:5), "Shivticha B'soch Mirma", all your business dealing are done with trickery. "B'Mirma MeiAnu Daas Oisi", but when it comes to Hashem's dealing suddenly we are most righteous.
This is Mirumaz in the pasuk "V'Haya Erkicha... BShekel HaKodesh". When you spend money on your own material needs you don't make many calculations whether you should spend the money or not. You only justify it after the fact. But when it comes to Shekel HaKodesh then suddenly, V'Haya Erkicha, we make all kinds of calculations that require graphs and charts, explaining why we cannot give.