Musnad Ahmad 27:1142

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Yazid ibn Abi Ziyad, from Ibn Abi Layla, from Ibn 'Umar, who said: We were in a military expedition and we fled. Then we intended to board a ship, but then we came to the Messenger of Allah, peace and blessings of Allah be upon him, and we said: "O Messenger of Allah, we are the ones who fled." He said: "No, rather you are the ones who return to the fight."