Abu Salih narrates from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Madinah is sacred from Ayr to Thawr. Whoever introduces an innovation in it or gives shelter to an innovator, upon him is the curse of Allah, the angels and all the people."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9953