I heard an amazing story several years ago. I’m not sure if I remember all the details correctly – maybe someone here has heard it and can correct any errors I make.
Basically someone non-frum owned a large store which was open on shabbos. Somehow he came in contact with a gadol (reb Moshe?) who promised him much hatzlocho if he were to close on shabbos. He decided he would do that. As shabbos approached, the store was packed with customers and he was unsuccessful in getting them to leave. Close to the start of shabbos, he screamed “Fire!!” and everyone ran out – many with unpaid for merchandise, and he quickly locked up the store in time for shabbos.
After that day his business grew tremendously, beyond anything he could have anticipated.