Fuad Yahya Feb 25, 2021:

This is a very challenging passage to translate. In answering your question, I addressed the term as posted: المفعول بها. The term, however, is part of a larger expression, بنت المفعول بها.

In any other context, the idiomatic translation of the former would be any misogynistic expletive that implies "a female who has no moral scruples against illicit sex." English is full of such terms.

The appropriate translation of the larger expression might be a bit awkward, because the practice in English when insulting a man is to impute meretricious conduct to his mother, but when a woman is insulted, the meretricious conduct is imputed to her directly. That alone will make a faithful translation awkward.

The situation here is even more challenging, because the narrator is attempting to advance the theory that the insult is not much of an insult if you examine the literal meaning of the term المفعول بها. Since the narrator's analysis is focused on the literal meaning of the term, not its moral connotations, the translation must follow suit. Otherwise, the narrator's analysis would be unintelligible to the reader. This is why I chose to provide a literal rendition, but this is also why the challenge you face in this passage is enormous.