Musnad Abu Ya'la al-Mawsili 154:151

Abu Khaythama narrated to us, Jarir narrated to us, from Yazid ibn Abi Ziyad, from Abd al-Rahman ibn Abi Layla, who said: Ibn Umar said: We were in an army that the Messenger of Allah (may Allah bless him and grant him peace) sent out. The people retreated in a retreat, and we were defeated. We were a group, and we said: "Let us flee into the land and not come to the Messenger of Allah (may Allah bless him and grant him peace) out of shame for what we have done." Then some of us said: "If we were to come to Medina, we could obtain provisions from it and equip ourselves." When we entered Medina, we said: "If we were to present ourselves to the Prophet (may Allah bless him and grant him peace)." He said: So we watched for him at the time of the dawn prayer. When the Messenger of Allah (may Allah bless him and grant him peace) came out, we said: "O Messenger of Allah, we are the ones who fled." The Messenger of Allah (may Allah bless him and grant him peace) said: "Rather, you are the ones who return to the fight (al-akkarun). I am the troop of the Muslims."