Musnad Abi Ya'la 569 — Sayyiduna Ali bin Abi Talib once became so

It is narrated from Yazid bin Umayyah al-Dili (may Allah have mercy on him) that Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) once became so severely ill that he was on the verge of death, and we became gravely afraid for his life. Then, when he recovered and his weakness went away, we said: "O Abu al-Hasan, congratulations on this health; praise be to Allah who granted you recovery; we had been greatly worried about you." He replied: "But I had no fear for my own life, because the truthful and believed one, the Messenger of Allah (peace and blessings be upon him), informed me that my death will not come until a blow is struck on this", and he pointed to the front left part of his head, "and this is dyed with its blood", and he took hold of his beard and said that the Messenger of Allah (peace and blessings be upon him) had said to me: "The most wretched person of this Ummah will kill you, just as the most wretched of such-and-such a clan of Thamud hamstrung the she-camel of Allah." The narrator says: The Messenger of Allah (peace and blessings be upon him) attributed him (the killer of the she-camel) to his close clan rather than to Thamud in general.