Selected Sayings of The Holy Prophet of Islam — Page 37
48. No'maan bin Basheer, God be pleased with him, said that he heard the Holy Prophet, peace and blessings of Allah be upon him, say: "It has been made clear what is lawful and what is forbidden. In between the two there are certain things undefined: most people do not know which category they belong to. Whoever keeps away from them safeguards his faith and his honour. Whoever steps into the doubtful is likely to have stepped into the forbidden area. He is like a shepherd who lets his flock graze around a forbidden area, while there is every danger that the flock may stray into it. Remember that every sovereign has a forbidden area. The forbidden area of Allah comprises the things He has prohibited. Beware! There is an organ in the body as long as it remains healthy, the entire body remains healthy. The moment it becomes diseased, the entire body will become diseased. Remember that this organ is the heart. " (Muslim) 37