Joseph Mokir Shabbat (the Sabbath) — "Joseph Who Honors the Sabbath" — was a man whose devotion to the Sabbath was so complete that it became the engine of his fortune. The Talmud (Shabbat 119a) tells his story as proof that honoring the Sabbath brings material as well as spiritual reward.
Joseph was a poor man who spent every coin he had on food for the Sabbath. While his neighbors ate simple meals during the week and saved their money, Joseph ate simply during the week and spent lavishly on the Sabbath. The finest fish, the best bread, the most aromatic spices — nothing was too good for the Sabbath table.
A wealthy gentile who lived nearby owned vast properties. Astrologers told him: "All your wealth will eventually pass to Joseph Mokir Shabbat." Terrified, the rich man sold all his property and used the money to buy an enormous diamond, which he sewed into his turban. "No one can take what I carry on my head," he reasoned.
But as he crossed a bridge, a gust of wind blew the turban into the river. A great fish swallowed the diamond. Fishermen caught the fish on a Friday afternoon and, looking for a buyer willing to pay a premium price so close to the Sabbath, they brought it to the one man in town who always bought the finest fish for the Sabbath: Joseph.
Joseph bought the fish. When he cut it open, the diamond tumbled out. He sold it for an enormous sum and became fabulously wealthy. A sage told him: "One who lends to the Sabbath, the Sabbath repays." Every coin Joseph had spent honoring the seventh day came back to him multiplied — through a fish, a diamond, and a gust of wind that was no accident at all.