Sayyiduna Abd al-Rahman bin Awf (may Allah be pleased with him) said: Umayyah asked me while I was walking with him: "O Abd al-Ilah, who is the man among you marked with an ostrich feather on his chest?" I said: "That is Sayyiduna Hamzah bin Abd al-Muttalib (may Allah be pleased with him)." He said: "He is the one who did all those things to us."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة الخوف / 6114
Sayyiduna al-Zubayr bin al-Awwam (may Allah be pleased with him) narrates the story of Sayyiduna Abu Dujanah, that is, Simak bin Kharashah (may Allah be pleased with him), at Uhud: the Prophet (peace and blessings be upon him) gave him his sword, and whenever he intended to fight, he would mark himself with a headband.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة الخوف / 6115