Musnad Ahmad 962:79

Yazid narrated to us, Hariz ibn Uthman narrated to us, from Abd al-Rahman ibn Maysarah, from Abu Umamah, that he heard the Messenger of Allah, peace and blessings of Allah be upon him, say: "There shall certainly enter Paradise, through the intercession of a man who is not a prophet, [a number of people] like the two tribes, or like one of the two tribes: Rabi'ah and Mudar." A man said: "O Messenger of Allah, is Rabi'ah not from Mudar?" He said: "I only say what I say."