Musnad Ahmad 658:204

Abu Sa’id narrated to us, he said: Shu’bah narrated to us, he said: I heard Abu Ishaq narrating from Al-Bara’, who said: The Messenger of Allah, peace and blessings of Allah be upon him, passed by some people of the Ansar in their gatherings and said: "If you must do so, then guide the way, return the greeting, and help the oppressed." And Muhammad ibn Ja’far said, from Shu’bah: Abu Ishaq from Al-Bara’, and Abu Ishaq did not hear it from Al-Bara’.