Musnad Abu Ya'la al-Mawsili 3:328

Zuhayr narrated to us, Jarir narrated to us, from al-A’mash, from Habib ibn Abi Thabit, from Tha’labah al-Hamani, who said: I heard Ali saying: The Messenger of Allah (ﷺ) said: "Whoever lies about me intentionally, let him take his seat in the Fire." And I bear witness that he was pointing to this, that this would be dyed with the blood of this—meaning his beard with the blood of his head.