The Medrash tells us that in order to explain the mitzva of the Shekalim, Hashem took out a coin of fire from underneath his Kisei HaKavod and showed it to Moshe. Rav Elyashiv asks two questions. First, had Moshe Rabbeinu never seen a coin in his life? Second, what exactly is Hashem doing hiding coins under his Kisei HaKavod?
He answers with a Tosfos in Chulin (42a) that Moshe
couldn't understand how money, the most earthly of all creations, can save
someone's neshama (Kofer Nefesh). So Hashem showed him a coin. Which coin? The
gemara in Bava Basra (11a) says that during a hunger year Munbaz HaMelech
emptied out his treasure chest to feed the poor people. His family became very
mad that he was squandering the royal wealth. To this he replied that he is not
losing the money, he saving the money up in Shamayim in a place where it will
last forever while they squander money down on earth where it will eventually
Rav Elyashiv says these are the coins that Hashem took out to
show Moshe. The coins that are given for tzedoka with Mesiras Nefesh are
precious and are saved by Hashem under the Kisei HaKavod. Moshe understood that
coins are made of destructive fire. They cause jealousy, cheating, stealing, and
murder. Hashem showed him that coins can be made out of productive fire. Coins
given for tzedoka can light the world and warm the world with their "Holy fire".
On these coins Hashem said "Kazeh Yitnu". If the people give in this fashion
then even coins can be Kofer Nefesh and money can redeem your soul.