The nephew of Abu Ruhm al-Ghifari (may Allah be pleased with him) relates that he heard Abu Ruhm (may Allah be pleased with him), who was among those who gave the pledge beneath the tree at the time of the Pledge of Ridwan, say: I went with the Messenger of Allah (peace and blessings be upon him) on an expedition. One night I halted, and then I began riding close to him (peace and blessings be upon him). Then the narrator related the (rest of the) hadith.
Hadith Referenceالمعجم الكبير للطبراني / باب الكاف / 16465