Musnad Abu Ya'la al-Mawsili 3:225

Suwayd ibn Sa'id narrated to us, Rushdin ibn Sa'd narrated to us, from Yazid ibn 'Abd Allah ibn Usamah ibn al-Had, from 'Uthman ibn Suhayb, from his father, who said: 'Ali said: The Messenger of Allah (ﷺ) said to me: "Who is the most wretched of the first [people]?" I said: "The hamstringer of the she-camel." He said: "You have spoken the truth. So who is the most wretched of the last [people]?" I said: "I have no knowledge, O Messenger of Allah." He said: "The one who will strike you upon this," and he pointed with his hand to the crown of his head. And he used to say: "I wish that your most wretched one had been sent forth, so that he might dye this from this," meaning his beard with the blood of his head.