Sahih Muslim Book 24, Hadith Number 5308.

Chapter : It Is forbidden to add false hair to one’s head or to pluck the eyebrow or to separate the teeth.

Sa’id b. Musayyib reported: Mu’awiya came to Medina and he addressed us and he took out a bunch of hair and said: What do I see that one of you does but that what the Jews did? (I can well recall) that when this act (adding of artificial hair) reached Allah’s Messenger (may peace be upon him), he named it as cheating.