Musnad Ahmad 1124:3

Ya'qub narrated to us, my father narrated to us, from Ibn Ishaq, Yazid ibn Abi Habib al-Masri narrated to me, from Abdullah ibn Rashid, from Abdullah ibn Abi Murrah—a man from his people—from Kharijah ibn Hudhafah al-Qurashi, then one of the Banu 'Adi ibn Ka'b, who said: The Messenger of Allah (peace and blessings of Allah be upon him) came out to us for the morning prayer and said: "Allah has aided you tonight with a prayer that is better for you than red camels." He said: So I said, "What is it, O Messenger of Allah?" He said: "The Witr, between the Isha prayer and the break of dawn."