Musnad Ahmad 658:19

'Affan narrated to us, 'Umar ibn Abi Za'idah narrated to us, he said: I heard Abu Ishaq, he said: A man said to Al-Bara', while joking with him: "You fled from the Messenger of Allah, may Allah bless him and grant him peace, and you were his companions." Al-Bara' said: "I bear witness regarding the Messenger of Allah, may Allah bless him and grant him peace, that he did not flee on that day. And I saw the Messenger of Allah, may Allah bless him and grant him peace, on the day of digging the trench, while he was carrying the dirt with the people, and he was reciting the words of Ibn Rawahah: 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 transgressed against us, And if they intend sedition, we refuse." He was raising his voice with it.