Sahih Muslim Book 1, Hadith Number 84.

Chapter : Precedence of the believers over one another and the superiority of the people of Yemen in this respect.

It is narrated on the authority of Abu Huraira that the Messenger of Allah observed: There have come the people of Yemen; they are tender of hearts, the belief is that of the Yemenites, the understanding (of the faith) is that of the Yemenites and sagacity is that of the Yemenites.