Mukhtasar Bukhari

Narrated Abu Huraira (may Allah be pleased with him): The Messenger of Allah (peace and blessings of Allah be upon him) said (before migration): "I have been commanded to go to a town which will overcome all other towns. It is called 'Yathrib', and it is Madinah. It expels evil people just as a furnace removes impurities from iron."