A prohibition (nahy) demands that an act be avoided, but its legal effects depend on whether the prohibition attaches to the act itself or to an associated external attribute.
Wrong in itself concerns the act's very legal nature. Wrong because of another factor concerns a prohibited condition or circumstance joined to an otherwise recognizable act. Consequently, sinfulness and legal validity may be distinct questions in some transactions.
Prayer at a disapproved time, a defective sale and divorce during menstruation should not all be assigned identical legal effects merely because the acts involve prohibition.
Identify the object of prohibition, the constituent elements of the act and the specific evidence governing invalidity, defect or enforceability.