Tracing Definition Of Maruf And Munkar From Sources
Can get a reference to some book. I tried to search in Mufradat of Raghib Asfahani and he said ” Al-Ma’ruf: It is the name of every word or deed whose goodness is proved by the intellect or the Shari’ah, and Munkar is the name of every thing which is considered bad according to the intellect and the Shari’ah.” He said aqal and Shariah, by Shariah and aqal also interest can be said a moral sin but it is not universally accepted.
There’s nothing grey about riba. People who earn riba know very well that it’s not good. Eating pig or dead meat are not maruf or munkar.