Musnad Ahmad 962:71

Waki’ narrated to us, Hammad bin Salamah narrated to us, from Abu Ghalib, from Abu Umamah, who said: A man came to the Prophet, may Allah bless him and grant him peace, while he was at the first Jamrah, and said: "O Messenger of Allah, which Jihad is the best?" He said: So he remained silent regarding him and did not answer him. Then he asked him at the second Jamrah, and he said to him the same thing. He said: Then, when the Prophet, may Allah bless him and grant him peace, had thrown the Jamrat al-Aqabah and placed his foot in the stirrup, he said: "Where is the questioner?" He said: "A word of justice in the presence of an oppressive ruler."