Task: Question Generation
Input (English):  Dr. Horace Bianchon discovers near the town of Vend me an abandoned manor: La Grande Bret che. Intrigued by the ruins, the doctor tries unsuccessfully to enter the house night after night. Upon returning to the inn where he is staying, he questions the locals about the house. Finally several locals, including a lawyer and the innkeeper, explain the story of the manor.
Madame de Merret, the late owner of the manor, forbid anyone from entering the house upon her death, be it workmen, visitors, or government officials, for 50 years. The lawyer was given the task, as well as funds, to ensure that her dying wish be accomplished.
Dr. Bianchon learned that Madame de Merret had a Spanish lover for a short period of her life. One day, Madame de Merret's husband returned early from a business trip when her lover was at the house. The lover hid himself in the closet, but the husband, hearing a sound, confronted his wife about the noise. Pressured by her suspicious husband, Madame de Merret swore upon a crucifix that there was no one in the closet, but threatened in turn to leave her husband if he were ever to open the closet out of suspicion. In response, Monsieur de Merret sent for a mason to wall up the closet, trapping the lover inside. Terrified, Madame de Merret passed along a message to the mason asking him to break a hole in the door when her husband was not looking before completely walling the closet off. The mason does that, and Madame de Merret catches a final glimpse of the maddened eyes of her lover through the hole. Once the closet was walled up completely, Madame and Monsieur de Merret stay in the bedroom for several days, listening to the muffled noise coming from the closet. Because of this traumatic experience, Madame de Merret declared her house off-limits upon her death.
Output (English): What item did Madame de Merret swear upon?