Sacred Citation & SourceReading a text requires care with the Arabic language. A command (amr), such as "establish the prayer" (2:43), normally shows obligation unless another sign shows it is only recommended. A prohibition (nahy) normally shows that something is forbidden. A general wording (amm) can be limited by a more specific one (khass): "Allah has permitted trade and forbidden riba" (2:275) gives a general permission for trade and a specific prohibition within it. Some words carry more than one meaning. "Divorced women shall wait for three quru'" (2:228): quru' can mean periods of purity or menstrual periods, so the Hanafi school counted menstrual periods while the Shafi'i and Maliki schools counted periods of purity. This is a respectful difference caused by language, not by neglecting the evidence.