An 11th-century book by a revered Baghdad Muslim scholar turns out to be a tongue-in-cheek guide for party crashers, according to the researcher who translated the book into English.

The tome was originally authored by al-Khatib al-Baghdadi, a well known scholar of the Prophet Mohammed's teachings.

According to Emily Selove of the University of Manchester, who did the translation, he wrote the book to remind readers "that every serious minded person needs to take a break."...