Mu'jam Kabir Tabarani 8018 — I went out with Sayyiduna Abu Umamah

Abu Ghalib narrates: I went out with Sayyiduna Abu Umamah al-Bahili (may Allah be pleased with him) to the mosque of Damascus. When we reached the door, there were some of the heads of the Khawarij. When he looked at them he wept and said: "What has Satan done!" — three times — "The dogs of Hell" — three times. Then he said: "The worst of the slain beneath the shade of the sky" — three times — "the one whom they killed was the best of the slain beneath the shade of the sky." I said: O Abu Umamah, are you saying this yourself, or is it something you heard from the Messenger of Allah (peace and blessings be upon him)? He said: "I could never be so bold. Do you read the verses at the beginning of Surah Al Imran?" "As for those in whose hearts is deviation, they follow what is ambiguous of it" [Al Imran: 7] — this was revealed about them; until you read the verse in the middle of Surah Al Imran: "On the Day when some faces will turn white and some faces will turn black" [Al Imran: 106] — this too was revealed about them. I said: O Abu Umamah, why are you weeping? He said: "These people were believers" — or he said: "were Muslims."