Musnad Ahmad 3:106

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from Simak ibn Harb, who said: I heard ‘Abbad ibn Zahir Abu Rawwa‘ say: I heard ‘Uthman delivering a sermon, and he said: "By Allah, we accompanied the Messenger of Allah (may Allah bless him and grant him peace) in travel and at home. He would visit our sick, follow our funeral processions, participate in military expeditions with us, and support us with little and much. Yet, there are people who try to teach me about him, even though it is likely that one of them has never seen him at all."