Ibn Hibban

Sayyiduna Nu’man bin Bashir (may Allah be pleased with him) narrates: I heard the Prophet Muhammad (peace and blessings be upon him) say: “The lawful is clear and the unlawful is also clear, and between them are some doubtful matters. (Here, the narrator is unsure about a word.) I present to you an example of this. Indeed, every king has a sanctuary, and the sanctuary of Allah is that which He has forbidden. So whoever grazes his animals around the sanctuary, it is possible that they may enter it. (At times, the narrator used these words:) Whoever grazes his animals around the sanctuary, eventually they begin to graze inside it. So whoever mingles with doubtful things, eventually he will cross into them.”