Musnad Ahmad 2:281

Hajjaj narrated to us, Shu'bah informed us, I heard Abu Jamrah al-Duba'i narrating from Juwayriyah ibn Qudamah, who said: I performed Hajj and came to Medina in the year in which Umar was struck. He said: He delivered a sermon and said: "I saw as if a red rooster pecked me once or twice" — Shu'bah was the one who doubted. He said: "He did not remain but a week until he was stabbed..." Then he mentioned the like of it, except that he said: "And I advise you regarding your Dhimmis (protected non-Muslim subjects), for they are the covenant of your Prophet." Shu'bah said: Then I asked him after that, and he said regarding the Bedouins: "And I advise you regarding the Bedouins, for they are your brothers, and the enemy of your enemy."