Musnad Abu Ya'la al-Mawsili 105:52

Muhammad ibn al-Faraj narrated to us, Muhammad ibn al-Zibriqan narrated to us, Musa ibn Ubaydah narrated to us, Sa'd ibn Ibrahim informed me, from whoever informed him, from Ammar ibn Yasir, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, the lawful is clear and the unlawful is clear, and between them are doubtful matters. Whoever avoids them, they will be a protection for his religion. And whoever falls into them, he is about to fall into the major sins, like the one who grazes around a sanctuary; he is about to fall into it. For every king, there is a sanctuary."