Musnad Ahmad 30:3396

Yazid narrated to us, Muhammad ibn ‘Amr informed us, from Abu Salamah, from Abu Hurairah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The people of Yemen have come to you. They are the weakest of hearts and the most tender of souls. Faith is Yemeni, and wisdom is Yemeni."