Kharijah bin Zayd bin Thabit (may Allah have mercy on him) narrates from his father Zayd (may Allah be pleased with him) that he said: The Messenger of Allah (peace and blessings be upon him) permitted me to take part in the fighting on the day of the Battle of the Trench (Khandaq), and he clothed me in a Coptic garment.
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 4726