"The halal is clear and the haram is clear, and between them
are matters unclear that are unknown to most people.
Whoever is wary of these unclear matters has absolved his
religion and honor. And whoever indulges in them has
indulged in the haram. It is like a shepherd who herds his
sheep too close to preserved sanctuary, and they will
eventually graze in it. Every king has a sanctuary, and the
sanctuary of Allah is what He has made haram. There lies
within the body a piece of flesh. If it is sound, the whole body
is sound; and if it is corrupted, the whole body is corrupted.
Verily this piece is the heart.“ [Bukhari & Muslim]