Sayyidah Aishah (may Allah be pleased with her) said that the Messenger of Allah (peace and blessings be upon him) said: "Whoever adds to this religion of ours, it is rejected."
Ibn Isa said that the Messenger of Allah (peace and blessings be upon him) said: "Whoever originates a new matter in this religion of ours, it is rejected."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 21196