Al-Matalib al-'Aliyah 4445 — The killing of Ali

It is narrated from Sayyiduna Suhayb (may Allah be pleased with him) that Sayyiduna Ali (may Allah be pleased with him) related that the Messenger of Allah (peace and blessings be upon him) asked me: "Who was the most wretched of the earlier people (of the former nations)?" I said: "The one who hamstrung the she-camel (of the people of Salih)." He (peace and blessings be upon him) said: "You have spoken the truth. Then who is the most wretched of the later people?" I said: "O Messenger of Allah, I have no knowledge of that." He (peace and blessings be upon him) said: "The one who will strike you here," and he (peace and blessings be upon him) pointed to the top of the head (the crown) of Sayyiduna Ali (may Allah be pleased with him). And Sayyiduna Ali (may Allah be pleased with him) used to say (often, out of longing for martyrdom): "I wish that most wretched one of yours would rise up (with his foul intention) and dye this with this," meaning that he would dye his blessed beard with the blood flowing from his head.
Imam Abu Ya'la narrated this hadith in his Musnad. Its chain contains the narrator Rishdin bin Sa'd, who is da'if (weak); however, supporting reports for the hadith exist in the six books and other books of hadith which strengthen it.