Musnad Ahmad 30:3851

Hussain narrated to us, Ibn Abi al-Zinad narrated to us, from his father, from al-A’raj, from Abu Hurairah, who said: The Messenger of Allah, may Allah bless him and grant him peace, said: "The people of Yemen have come to you; they are the weakest of hearts and the softest of souls. Understanding (al-fiqh) is Yemeni, and wisdom is Yemeni."