According to the story in the Apocrypha (see February blog), Tobias has used the heart and liver from the giant fish to make a potent smoke. This drove away the demon that had devoured Sarah's previous seven husbands, and in the morning: "So the maidservant opened the door, and went in, and found them both sleeping, and came forth and told them that he was alive. And Raguel blessed God."
This picture of wedded bliss shows a very upmarket bedroom, with splendid damask coverlet, and, of course, Tobias' faithful dog.
Tobias and Sara on their wedding night. German, c. 1520
© Victoria & Albert Museum