Musnad Abu Ya'la al-Mawsili 246:11

Zuhayr narrated to us, Yazid narrated to us, Ibn Abi Dhi'b informed us, from al-Harith ibn 'Abd al-Rahman, from Muhammad ibn Jubayr ibn Mut'im, from his father, who said: We were with the Messenger of Allah (may Allah bless him and grant him peace) on a journey of his, and he said: "There will emerge upon you the people of Yemen, as if they were the clouds; they are the best of those who are on the earth." A man from the Ansar said: "Except for us, O Messenger of Allah?" He remained silent. Then he repeated it, and he remained silent. Then he repeated it a third time: "Except for us, O Messenger of Allah?" He said a weak word: "Except for you."