Musnad Ahmad 1124:1

Yazid ibn Harun narrated to us, Muhammad ibn Ishaq informed us, from Yazid ibn Abi Habib, from Abdullah ibn Rashid al-Zufi, from Abdullah ibn Abi Murrah al-Zufi, from Kharijah ibn Hudhafah al-Adawi, who said: The Messenger of Allah (peace and blessings of Allah be upon him) came out to us one morning and said: "Verily, Allah has aided you with a prayer that is better for you than red camels." We said: "And what is it, O Messenger of Allah?" He said: "The Witr, between the Isha prayer and the break of dawn."