Musnad Ahmad 658:102

Muhammad ibn Ja‘far and ‘Affan narrated to us, they said: Shu‘bah narrated to us, from Abu Ishaq, who said—‘Affan said: Abu Ishaq informed us—from al-Bara’, and Abu Ishaq did not hear it from al-Bara’. He said: The Messenger of Allah (peace and blessings of Allah be upon him) passed by a group of people sitting in the road. He said: "If you must do so, then guide the way, return the greeting, and aid the oppressed." ‘Affan said: "And assist." Abu Sa‘id narrated it to us, Shu‘bah narrated to us, he said: I heard Abu Ishaq say: "Assist the oppressed." Aswad narrated it to us, he said: Isra’il narrated to us, Abu Ishaq narrated to us, from al-Bara’, and he said: "Assist the oppressed." And likewise, Husayn said: "Assist," from Isra’il.