Musnad Ahmad 761:3

Ya'qub narrated to us, my father narrated to us, from Ibn Ishaq, and Ibn Shihab mentioned, from Ibn Akimah al-Laythi, from the nephew of Abu Ruhm al-Ghifari, that he heard Abu Ruhm Kulthum ibn Husayn—and he was one of the companions of the Messenger of Allah, peace and blessings of Allah be upon him, who pledged allegiance under the tree—saying: I went on the expedition of Tabuk with the Messenger of Allah, peace and blessings of Allah be upon him. He mentioned the hadith, except that he said: I began to hold my riding beast back from him until my eyes overcame me. And he said: "What happened to the black, curly-haired, short people?" I said: "By Allah, I do not recognize those among us." Until he said: "Yes, those who have livestock at Shabakat Sharkh." He said: So I remembered them among the Banu Ghifar, but I did not recall them until I remembered that they were a group from Aslam who were allies among us. So I said: "O Messenger of Allah, those are a group from Aslam who are our allies."