Abu Ghalib said: I was in Damascus in the time of Abd al-Malik when the heads of the Khawarij were brought and set up on wooden poles. I came to see whether there was anyone among them whom I knew, and there I saw Sayyiduna Abu Umamah (may Allah be pleased with him). I went near him and looked at the poles, and he said: "The dogs of Hell" — three times — "the worst of the slain beneath the sky, and those whom they killed are the best of the slain beneath the sky" — he said this three times. Then he began to weep. I said: O Abu Umamah, why are you weeping? (He said:) They were upon our own religion; then I remembered the end they are heading towards tomorrow. I said to him: Is this something you say from your own opinion, or something you heard from the Messenger of Allah (peace and blessings be upon him)? He said: "Had I not heard it from the Messenger of Allah (peace and blessings be upon him) once, or twice, or three times — up to seven times — I would not have narrated it to you. Do you not read this verse in Surah Al Imran?" "On the Day when some faces will turn white and some faces will turn black" [Al Imran: 106] to the end of the verse, "And as for those whose faces turn white, they will be in the mercy of Allah; they will abide therein forever" [Al Imran: 107]. Then he said: "The Jews split into seventy-one sects: seventy in Hell and one in Paradise. The Christians split into seventy-two sects: seventy-one sects in Hell and one in Paradise. And this Ummah will split into seventy-three sects: seventy-two in Hell and one in Paradise." We said: Describe them to us. He said: "Al-Sawad al-A'zam (the greatest body)."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 8020