It is narrated from Sayyiduna Mughirah bin Shu'bah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever attributes to me something I did not say, let him take his seat in the Fire."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 18208