Sahih Muslim Book 7, Hadith Number 3178.

Chapter : Eminence of Medina, Allah’s Apostle (may peace be upon him) showered blessings upon it. Its sacredness and unlawfulness of hunting and lopping of trees and demarcation its precincts.

‘Aisha (Allah be pleased with her) reported: When we came to Medina, and it was an unhealthy, uncongenial place, Abu Bakr fell sick and Bilal also fell sick; and when Allah’s Messenger (may peace be upon him) saw the illness of his Companions he said: O Allah, make Medina as congenial to us as you made Mecca congenial or more than that; make it conducive to health, and bless us in its sa’ and in its mudd, and transfer its fever to al-juhfa.