Prophet Muhammad (pbuh) said: “What is lawful is evident and what is unlawful is evident, and in between them are the doubtful things which many people do not know. So he who guards against doubtful things keeps his religion and honor blameless, and he who indulges in doubtful things indulges in fact in unlawful things, just as a shepherd who pastures his animals round a preserve will soon pasture them in it. Beware, every king has a preserve, and the things Allah has declared unlawful are His preserves. Beware, in the body there is a piece of flesh; if it is sound, the whole body is sound and if it is corrupt, the whole body is corrupt.” [Bukhari & Muslim]