Abu Ghalib (may Allah have mercy on him) said: "I was in Syria, and Sayyiduna Abu Umamah Sudayy bin Ajlan (may Allah be pleased with him), the Companion of the Messenger of Allah (peace and blessings be upon him), was also there; he was a friend of mine. Some of the heads of the Haruriyyah (the Khawarij) were brought and thrown down on the steps. Sayyiduna Abu Umamah (may Allah be pleased with him) came, entered the mosque, prayed two rak'ahs, and then went towards the heads. I said (to myself): I will follow him and hear what he says. So I followed him until he stopped by them and wept, then said: 'Subhan Allah! What Iblis does to this Ummah!' Then he said: 'These are the dogs of Hell, these are the dogs of Hell, these are the dogs of Hell.' Then he said: 'They are the worst of the slain who have been killed beneath the shade of the sky, and the best of the slain are those whom they killed.' Then he recited this verse: (On the Day when some faces will turn white and some faces will turn black; as for those whose faces turn black, (it will be said:) Did you disbelieve after your faith?). Then he turned towards me and saw me. Abu Ghalib said: He took hold of my forearm and said: 'Do you live in a land where these people are many?' meaning Iraq. I said: Yes. He said: 'May Allah protect you from becoming one of them.' I said: O Abu Umamah! What you said, 'the dogs of Hell', did you say it from your own opinion, or is it something you heard? He said: 'Subhan Allah! Then I would be very bold indeed! No, rather I heard it from the Messenger of Allah (peace and blessings be upon him), not once, not twice, not three times, not four times, not five times, not six times, not seven times (but more often than that).'"
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from Mubarak except Ismah bin al-Mutawakkil."
Hadith Referenceالمعجم الأوسط / باب الميم / 7660
Hadith Takhrij«أخرجه الحاكم فى «المستدرك» برقم: 2669، 2670، والترمذي فى «جامعه» برقم: 3000، وابن ماجه فى «سننه» برقم: 176، والبيهقي فى «السنن الكبرى» برقم: 16884، 16883، وأحمد فى «مسنده» برقم: 22581، 22613، 22638، 22690، 22745، والطيالسي فى «مسنده» برقم: 1232، والحميدي فى «مسنده» برقم: 932، وابن حجر فى «المطالب العالية» برقم: 2974 / 2، 2974 / 1، وعبد الرزاق فى «مصنفه» برقم: 18663، وابن أبي شيبة فى «مصنفه» برقم: 39047، والطحاوي فى «شرح مشكل الآثار» برقم: 2519، والطبراني فى «الكبير» برقم: 7553، 8036، 8033، 8034، 8035، 8037، 8041، 8042، 8038، 8039، 8040، 8044، 8045، 8046، 8051، 8049، 8050، 8053، 8052، 8054، 8055، 8056، والطبراني فى «الصغير» برقم: 33، 1096، والطبراني فى «الأوسط» برقم: 7202، 9085»