The prophet Elijah came to a young man with a simple offer. He could have seven good years of prosperity, either at the beginning of his life or at the end. The choice was his.
The young man went home to his wife to discuss it. His wife's counsel became famous in the tradition. "Choose the seven prosperous years now, while we are young," she said. "If we act charitably during those seven years and use the wealth for tzedakah, Heaven may extend the blessing, and we may prosper for many more years. But if we wait until we are old, and we squander the seven years on our own comforts, there will be no chance to earn a second span. Prosperity that ends with death teaches nothing."
The young man went back to Elijah and asked for the seven years immediately. The prophet handed him a single lucky dinar and told him to use it with care. The young man took the dinar home, and from that coin his business grew wildly. Within the seven years he had become wealthy beyond his old imagination.
Every month, the couple kept an account of their charity. They fed travelers. They dowered poor brides. They paid the taxes of neighbors who could not. They supported students of Torah. They built a house that was, effectively, a public charity post.
At the end of the seventh year, Elijah returned. He asked for his lucky dinar back. The young man placed the coin on the table and, next to it, the full ledger of the charitable deeds it had enabled. Elijah studied the ledger in silence. When he looked up, he told the young man to keep the dinar. The seven-year term had been renewed indefinitely. The couple prospered into old age and left their children a household of blessing (Gaster, Exempla No. 317).
The lesson the sages drew is that wealth held in a charitable fist is held by Heaven. Wealth held in a greedy fist is held only for seven years at a time.