Musannaf Ibn Abi Shayba 28:697

Waki’ narrated to us, he said: Shu’bah narrated to us, from Qays ibn Muslim, from Tariq ibn Shihab al-Ahmasi, who said: The Banu ‘Utarid raided with one hundred men from the people of Basra, and they were reinforced by ‘Ammar from Kufa. ‘Ammar went out before the battle and said, "We are their partners in the spoils." A man from the Banu ‘Utarid stood up and said, "O you mutilated slave"—and his ear had been injured in the way of Allah—"do you want us to divide our spoils with you?" ‘Ammar said, "You taunted me for the most beloved of my two ears, or the best of my two ears." He wrote to ‘Umar regarding that, and ‘Umar wrote back: "The spoils belong to those who witnessed the battle."