The Prophet ﷺ said, "Do not lie about me, for whoever lies about me shall enter the Fire."
قال النبي ﷺ: لا تكذبوا علي، فإنه من كذب علي فليلج النار.
Bukhari narrated it in the Book of Knowledge (106), and Muslim in the Introduction (1), both through routes going back to Shubah, from Mansur, from Rabi bin Harash, that he heard Ali, and he related it. The wording given is that of Bukhari, and Muslim's wording is the same except for the phrase, "let him enter the Fire." In Muslim's version it is, "he enters the Fire."