It is narrated from Sayyiduna Wathilah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The greatest lie in the sight of Allah is that someone attributes to me what I did not say, or ascribes himself to someone other than his patrons (mawali), or makes his eyes see in a dream what they did not see."
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18393