Jami` at-Tirmidhi, Volume 5, Book 44, Hadith 3000 (DarusSalam) ⓘ
Narrated Abu Ghalib: "Abu Umamah saw heads (of the Khawarij) hanging on the streets of Damascus. He said: 'The dogs of the Fire and the worst dead people under the canopy of the heavens. The best dead men are those whom these have killed.' He then recited: On the Day when some faces will become white and some faces will become black... (3:106) until the end of the Ayah. I said to Abu Umamah: 'Did you hear it from the Messenger of Allah?' He said: 'If I had not heard it but one time, or two times, or three times, or four times - until he reached seven - I would not have narrated it to you.'"
حَدَّثَنَا أَبُو كُرَيْبٍ، حَدَّثَنَا وَكِيعٌ، عَنِ الرَّبِيعِ بْنِ صَبِيحٍ، وَحَمَّادِ بْنِ سَلَمَةَ، عَنْ أَبِي غَالِبٍ، قَالَ رَأَى أَبُو أُمَامَةَ رُءُوسًا مَنْصُوبَةً عَلَى دَرَجِ مَسْجِدِ دِمَشْقَ فَقَالَ أَبُو أُمَامَةَ " كِلاَبُ النَّارِ شَرُّ قَتْلَى تَحْتَ أَدِيمِ السَّمَاءِ خَيْرُ قَتْلَى مَنْ قَتَلُوهُ " . ثُمَّ قَرَأَ : ( يَوْمَ تَبْيَضُّ وُجُوهٌ وَتَسْوَدُّ وُجُوهٌ ) إِلَى آخِرِ الآيَةِ قُلْتُ لأَبِي أُمَامَةَ أَنْتَ سَمِعْتَهُ مِنْ رَسُولِ اللَّهِ صلى الله عليه وسلم قَالَ لَوْ لَمْ أَسْمَعْهُ إِلاَّ مَرَّةً أَوْ مَرَّتَيْنِ أَوْ ثَلاَثًا أَوْ أَرْبَعًا حَتَّى عَدَّ سَبْعًا مَا حَدَّثْتُكُمُوهُ . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ وَأَبُو غَالِبٍ يُقَالُ اسْمُهُ حَزَوَّرُ وَأَبُو أُمَامَةَ الْبَاهِلِيُّ اسْمُهُ صُدَىُّ بْنُ عَجْلاَنَ وَهُوَ سَيِّدُ بَاهِلَةَ .
also referenced under: Hadith 3000 (Reference) & Book 47, Hadith 3270 (In-Book)