Musannaf Ibn Abi Shayba 38:99

Al-Fadl ibn Dukayn narrated to us, he said: Musa ibn Qays narrated to us, he said: I heard Hujr ibn 'Anbas say: It was said to Ali on the day of Siffin, "A barrier has been placed between us and the water." He said: "Send for al-Ash'ath." He said: So he came, and he (Ali) said: "Bring me the armor of Dir' ibn Sahar, a man from the Banu Bara." Then he poured it upon him, and he went to them. He fought them until he removed them from the water.