Musannaf Ibn Abi Shayba 28:83

Abu Dawud al-Tayalisi narrated to us, from Ibn al-Ashhab, who said: I said to al-Hasan, "O Abu Sa'id, a man is naked, so he puts on a garment, or he is unarmed, so he puts on armor." He said: "He may do so. But when the distribution (of spoils) is present, let him be present for it."