Sayyiduna Abu Ruhm al-Ghifari (may Allah be pleased with him), who was one of the Companions of the Messenger of Allah (peace and blessings be upon him) who gave the pledge beneath the tree, said: I took part with the Messenger of Allah (peace and blessings be upon him) in the expedition of Tabuk. When he (peace and blessings be upon him) was returning, he travelled one night at al-Akhdar. I was riding close to him (peace and blessings be upon him), and drowsiness overcame us. I kept waking with a start to find that my mount had come close to his (peace and blessings be upon him) mount, and its closeness alarmed me, until I feared that it might strike his (peace and blessings be upon him) foot in the stirrup, so I would pull my mount back. Until, during part of the night, my eyes were overcome by sleep, and my mount pressed against the mount of the Messenger of Allah (peace and blessings be upon him) at the stirrup and struck his (peace and blessings be upon him) foot. I only woke up at his (peace and blessings be upon him) saying "Hass!" (Ouch). I said: "O Messenger of Allah! Seek forgiveness for me." He (peace and blessings be upon him) said: "Keep going." Then the Prophet (peace and blessings be upon him) began asking me about those of Banu Ghifar who had stayed behind, and I told him. Then he (peace and blessings be upon him) asked: "What became of the tall, red-complexioned people with sparse beards?" So I told him of their staying behind. Then he (peace and blessings be upon him) asked: "What became of those black, locust-like, short people whose livestock graze at Shabakah?" I tried to recall them among Banu Ghifar but could not, until I remembered that they were a group of Banu Aslam who had stayed behind. The Prophet (peace and blessings be upon him) said: "What prevented any one of them, while staying behind, from mounting an energetic man on one of his camels and sending him in the path of Allah? For the hardest thing for me is that my own people, the Muhajirun of Quraysh, the Ansar, Aslam and Ghifar, should stay behind from me."
Al-Tabarani (may Allah have mercy on him) said: Muhammad bin Ishaq narrated it from al-Zuhri, and mentioned Ibn Ukaymah as an intermediary between (al-Zuhri and) the nephew of Abu Ruhm.
Hadith Referenceالمعجم الكبير للطبراني / باب الكاف / 16466