Ammar al-Duhni said: Sayyiduna Ali (may Allah be pleased with him) passed by Ka'b (al-Ahbar), and Ka'b said: "From the offspring of this man (meaning Ali (may Allah be pleased with him)) a man will be killed along with a band of people, the sweat of whose horses will not dry before they arrive before Muhammad (peace and blessings be upon him)." Then Hasan (may Allah be pleased with him) passed by, and the people asked: O Abu Ishaq! Is it this one? Ka'b said: No. Then Husayn passed by, and they asked: Is it this one? Ka'b said: Yes.
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2838