Musannaf Ibn Abi Shayba 27:689

'Abd al-Rahim narrated to us, from Isma'il, from Qays, who said: The Messenger of Allah (may Allah bless him and grant him peace) said to 'Abdullah ibn Rawahah, "Will you not stir the riding beasts for us?" 'Abdullah said, "I have abandoned my poetry." 'Umar ibn al-Khattab said, "Listen and obey." So he descended, driving the riding beast of the Prophet of Allah (may Allah bless him and grant him peace), and saying: "O Allah, were it not for You, we would not have been guided, Nor would we have given charity, nor would we have prayed. So send down tranquility upon us, And make firm the feet if we meet [the enemy]. Indeed, those who have disbelieved have oppressed us." The Messenger of Allah (may Allah bless him and grant him peace) said, "O Allah, have mercy on him." 'Umar said, "It has become incumbent."