An-Nawawi Hadith - 6

إِنَّ الْحَلاَلَ بَيِّنٌ، وَإِنَّ الْحَرَامَ بَيِّنٌ، وَبَيْنَهُمَا أُمُورٌ مُشْتَبِهَاتٌ لاَيَعْلَمُهُنَّ كَثِيرٌ مِنَ النَّاسِ، فَمَنْ اتَّقَى الشُّبُهَاتِ فَقَد اسْتَبْرَأَ لِدِيْنِهِ وَعِرْضِهِ، وَمَنْ وَقَعَ فِي الشُّبُهَاتِ وَقَعَ فِي الْحَرَام، كَالرَّاعِي يَرْعَى حَوْلَ الْحِمَى يُوشِكُ أَنْ يَرْتَعَ فِيهِ، أَلاَ وَإِنَّ لِكُلِّ مَلِكٍ حِمًى، أَلاَ وَإِنَّ حِمَى اللهِ مَحَارِمُهُ، أَلاَ وَإِنَّ فِي الْجَسَدِ مُضْغَةً، إِذَا صَلُحَتْ صَلَحَ الْجَسَدُ كُلُّهُ، وَإِذَا فَسَدَتْ فَسَدَ الْجَسَدُ كُلُّهُ، أَلاَ وَهِيَ الْقَلْبُ رَوَاهُ البُخَارِيُّ وَمُسْلِمٌ

On the authority of Abu 'Abdullah al-Nu'man bin Bashir, radiyallahu 'anhu, who said: I heard the Messenger of Allah, sallallahu 'alayhi wasallam, say: "Truly, what is lawful is evident, and what is unlawful is evident, and in between the two are matters which are doubtful which many people do not know. He who guards against doubtful things keeps his religion and honour blameless, and he who indulges in doubtful things indulges in fact in unlawful things, just as a shepherd who pastures his flock 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 flesh; if it is sound, the whole body is sound, and if it is corrupt, the whole body is corrupt, and behold, it is the heart." [Al-Bukhari and Muslim]