Mustadrak al-Hakim — Hadith 2580

It is narrated from Sayyiduna Abd al-Rahman bin Awf (may Allah be pleased with him) that he said: (On the day of Badr) Umayyah bin Khalaf asked me, while I was holding his hand and the hand of his son Ali (leading them away as captives): "O Abd al-Ilah, who is that man in your army who has an ostrich feather fixed on his chest as a mark?" I said: "That is Sayyiduna Hamzah bin Abd al-Muttalib." Umayyah said: "That is the one who did great deeds against us (in the battle)."
This hadith is sahih (authentic) on the condition of Imam Muslim, but he did not record it. Imam Ibn Khuzaymah recorded it in the chapter which establishes the concession of putting on some mark on the battlefield so that one may be recognised.