A religious couple got free dinner

I work at the Thai restaurant during the weekend as my part time job. There were two regular customers coming almost every other Saturday night for dinner. They are catholic I believe. They used to prayer to God before they start their meals. In tonight occasion, a pair of young married couple saw their prayer, and felt so inspired. They secretly told me that they will pay for their check tonight. When the religious customers finished their meal, I told them that the young couple already paid for their meals, and they already left. They felt so grateful, and left me $20 tip. What a windfall for tonight. Well, to be religious, you might get a sudden reward from your service to God.