Musannaf Ibn Abi Shayba 28:1168

Affan narrated to us, he said: Hammad bin Salamah narrated to us, he said: Ata bin al-Sa’ib informed us, he said: Abd al-Rahman bin Abi Layla narrated that two men fled on the day of Maskin from the Kufa military expedition. They came to Umar, and he reproached them and took them to task with his tongue severely, and he said: "You two fled." He intended to send them to the Basra military expedition, but they said: "O Commander of the Faithful, no, rather return us to the military expedition from which we fled, so that our repentance may be through it."